I usually go level by level because I make my decisions about what options to pick based off of the synergies of the other characters in my group. A choice that is optimal for my character may be suboptimal for the party as a whole and a “lesser” choice for my character in a vacuum may be an ideal choice for the party as a whole. This is a team game and none of the optimization guides take other characters into account, mainly because there are SO many options once you start looking at optimizing a group of characters that it’s almost impossible to analyze all of them.