Open-circuit voltage can still be relatively high yet the cell be useless for the need (eg, anything with a motor).
I try burning down AAs first in my TK4A, then SF13, finally my bobofett light to really wring ’em dry. Watching for any hint of an impending leak, of course.
Any mismatch means that 1 out of 4 in my ’4A will typically start being reverse-charged when the light goes orange to red. Toss that, other 3 are decent, will burn down 2 of those in my ’13 ’til it starts acting up (both weak, or 1 of 2 being dead), then the stragglers go into bobofett.
No “voltage” to speak of, just performance/indications when to have a look at ’em.
Key is to watch ’em to make sure those hateful little cells don’t do what they’re (in)famous for.