You don't necessarily have enough sheep.

By casting Yan, Tan, Tether, you can treble your flock. For one hour, your trebled flock will also do 3 times the damage it would have done. At higher levels, you can quadruple and quintuple.

If you wish to treble your trebled flock, you must take a level of exhaustion, and so on and so forth, until you die.

If the wielder dies but the crook remains, the trebled flock will remain their size, but without a shepherd to maintain them most will die.

If the spell is dispelled, the extra sheep dissolve into the fey

If the Crook of Cirb is destroyed before the spell is dispelled, all the extra sheep will instantly die.