depends. your work capacity, recovery ability, food intake, sleep patterns, can all affect this on a daily basis. these variables change over time. some measured in days, others in months or even years.
what is meant by how long in stating as long as it takes, you do just that. so if you need to do 3x10 you rest long enough to be recovered to be able to hit 10 reps on all sets whether that be 30 seconds or 5 minutes. this is less important on a bodybuilding plan in that you need to keep the reset shorter and focus on the muscle working and not worry so much about number of reps. if you are doing a strength program you can go much longer on rest and reps done are more important in that you do not ever want to miss a rep. strength programs are also based upon percentages so volume and intensity is already closely monitored. if you miss reps you either did not recover from the previous workout, did not recover from the previous set, or estimated your max too high.
"Rest long enough to be able to hit 10 reps on all sets"
The implications of this, if im understanding you correctly, would be that id be resting 3 minutes for most of my volume sets. To do this and get adequate volume to disrupt homeostasis, id be in the gym forever. I also watch guys much larger than me at the gym, and they seem to slowly lose repetitions over time as they progress through their volume sets, implying they are not fully recovered.
Im sure im misunderstanding something, but what i dont know. Thank you SO much for the detailed replies, both of you. I realize it takes time and can be frustrating to have someone not really "get it" and keep asking questions. Thank you thank you
To reiterate
5/3/1 sets: full recovery, 3-5 minute rests, little to no loss in repetitions for straight sets.
Volume sets:
30 second rests: could cut my reps in half.
1 minute: by a few
2 minutes: by 1 or 2
3 minutes: minimal rep loss