Hey all, I would really like to receive feedback on my take on the 5e/One D&D resting rules system. I cover why I feel this is needed, and how I address the issue. I try my best to make as few changes to the overall 5e/One D&D infrastructure as possible and work within the overall system.

Motivation: Adhering to the recommended 6-8 encounters a day can be a slog, particularly for overland, city, or traveling portions of an adventure. Adjusting to using 1-2 deadly encounters a day can become tedious, inflexible, and make the PCs feel weak. Gritty Realism rules (from the DMG) solves this problem very well, however, it breaks apart when the adventure shifts to high density encounter phases, like dungeons. Some have suggested a two-speed system (Gritty Realism outside of dungeons and normal rules in dungeons), but I feel this takes agency away from PCs and makes D&D too rigid and unnatural. My proposed system is to have 1 set of rules to enable: 

1. Dungeon delving or other high-density encounter phases.
2. Traveling, overland, city adventuring or other low density encounter phases.
3. Give the Players agency and power to dictate their own pace and response to situations. 

Goal: Have a singular rest and recovery system that is accommodative to the epic adventure or survival-type adventure in a way that gives PCs the agency to dictate their pace and preparedness while at the same time giving DMs the flexibility to work with various timescales and density of encounters. (i.e., not always 6-8 medium encounters a day, or always 1-2 deadly encounters a day).

Overview: The system breaks down into two parts: The first is simply borrowing the Gritty Realism rules already in the official DMG. The second is a new Rally mechanic to give players agency to deal with times of high-density encounters (i.e. dungeons) and simulate the feel of pressing forward through sheer will. Note that I am adopting the new Exhausted Condition from the One D&D Rules.

Gritty Realism Portion (almost entirely taken straight out of the DMG):

1. Short Rest. A Short Rest requires 8 hours of resting to accomplish. PCs must expend HD to recover Hit Points.
   
   
2. Long Rest. A Long Rest requires 5 days of resting to accomplish. The character must expend HD to recover Hit Points. You recover half your maximum HD pool at the end of the long rest. You can only benefit from a Long Rest every 24 hours. A successful Long Rest recovers all levels of the Exhausted Condition.
   • A Long Rest can only occur in a comfortable, non-hostile Safe Spot, such as a friendly town, inn, or well-prepared outpost with accommodations. In general, if the party would need to keep watch or otherwise remain alert, then they are not in a Safe Spot.
     
     
   • Optional Rule: The DM can adjust the difficulty of the adventuring by allowing the Party a Group Wisdom Check (Survival (DC 15) if they have the time, resources, inclination, and appropriate safety/dry location in the wilderness (i.e., like Weathertop). Rangers/Druids automatically succeed their check.
3. Expending Hit Dice. When performing a Short Rest or Long Rest, each character must use one charge of a Healer's Kit to expend any number of Hit Dice to recover hit points. When recovering hit points in this manner, any character can administer the Healer's Kit and perform an Intelligence Check (Medicine, DC 10) to effectively use the Healer's Kit and grant an additional +1 hit point per HD spent. A character with the Healer Feat automatically succeeds in this check.
   • Optional Rule: The DM can adjust the difficulty of adventuring by scaling the amount of hit points gained from Medicine Check or including some amount of free hit point recovery. Additional flavor can be accomplished by, for example, requiring an Herbalism Kit to perform the optional Medicine Check.

New Mechanic - Rally

1. At any time, the party can decide their situation requires pressing forward through sheer will to address the challenges ahead of them and the party can collectively decide to Rally.
   • Rally allows the party to Short Rest in 1 hour and Long Rest in 8 hours.
   • The party can choose to continue to Rally for consecutive days, bearing no penalties during their Rally. At the end of the last day of rallying, the party receives X number of levels of the Exhausted Condition equal to the number of days spent rallying.
   • Performing a Long Rest during a Rally does not remove any levels of the Exhausted Condition.

 Miscellaneous 

1. Leomund's Tiny Hut is a great utility spell against wild animals/dumb enemies and the elements. The spell could be a fine solution for establishing a location for a Short Rest, however, it does not serve as a Safe Spot for purposes of a Long Rest. Furthermore, the spell isn't intended to act as a bunker or garrison. Below are some optional ideas to bring Leomund's Tiny Hut in-line with its intended spirit.
   • Optional Rule: Casting the spell as a ritual consumes components totaling 10g. This causes the PC to choose between gold or spell slot as a resource to use this spell.
   • Optional Rule: Missiles, weapons, and most spell effects can pass through the hut (both in and out) without affecting it.

I tried to keep things as simple as possible, you'll note that there is only 1 new mechanic (Rally) which is straightforward. Everything else is largely taken from the existing DMG Gritty Realism rules, which perform very well during overland/traveling/city phases of adventuring. As I noted earlier, the only problem with the Gritty Realism rules was when the adventure shifts to dungeons and other high-density encounter phases. I believe the Rally mechanic above solves this in a way that gives the players the capacity to decide their own pacing and response to urgency with regards to resting/recovery. 

Let me know what you think! Thanks.

If I was a player I wouldn’t enjoy it myself, however every party is different and if your group will enjoy this then go for it ;)

I agree that this is a problem and have tried a few things myself. I find the gritty stuff to be a bit constraining when you're trying to do a faster-paced narrative.

I try to keep it as simple as possible, so my rule is just that you can only take a "full" long rest in an area of civilization. When you're camping or sailing on a ship, you still need to sleep every night but only get the benefit of a short rest. On extended trips or dungeon delves, I will often throw in ways to recover limited resources - for example a fey-touched spring that grants a couple hit dice and spell slots - or give resources as bonuses for high degrees of success or particularly inspiring moments. It's got issues like any other "fix," but it's been working for me so far.

Quote from scatterbraind >>

I agree that this is a problem and have tried a few things myself. I find the gritty stuff to be a bit constraining when you're trying to do a faster-paced narrative.

I try to keep it as simple as possible, so my rule is just that you can only take a "full" long rest in an area of civilization. When you're camping or sailing on a ship, you still need to sleep every night but only get the benefit of a short rest. On extended trips or dungeon delves, I will often throw in ways to recover limited resources - for example a fey-touched spring that grants a couple hit dice and spell slots - or give resources as bonuses for high degrees of success or particularly inspiring moments. It's got issues like any other "fix," but it's been working for me so far.

 
My fix was super simple as well. I made it so you regain all of your hit dice on a long rest, but only half of your hit points. Basically I just switched ‘em. This incentivizes the party to want to short rest so they can use their free resource and hold off long resting until they’ve spent most of all of their hit dice. Worked like a charm.

Quote from IamSposta >>

Quote from scatterbraind >>

I agree that this is a problem and have tried a few things myself. I find the gritty stuff to be a bit constraining when you're trying to do a faster-paced narrative.

I try to keep it as simple as possible, so my rule is just that you can only take a "full" long rest in an area of civilization. When you're camping or sailing on a ship, you still need to sleep every night but only get the benefit of a short rest. On extended trips or dungeon delves, I will often throw in ways to recover limited resources - for example a fey-touched spring that grants a couple hit dice and spell slots - or give resources as bonuses for high degrees of success or particularly inspiring moments. It's got issues like any other "fix," but it's been working for me so far.

 
My fix was super simple as well. I made it so you regain all of your hit dice on a long rest, but only half of your hit points. Basically I just switched ‘em. This incentivizes the party to want to short rest so they can use their free resource and hold off long resting until they’ve spent most of all of their hit dice. Worked like a charm.

 Huh. That seems like a really good system. Maybe I'll have to try that for my DotMM campaign where I chose to ignore time of day... so instead of "No you can't long rest cuz I don't feel like it's been long enough" I can just have them spend all their hit dice or something before they long rest.