Actually, I made this thread to see how many reps in a set people can complete in a certain percentage of 1RM.
Well first off I've come to appreciate Wendler's insistence that a true 1RM is fiction. That's why I consider the 1RM used for calculating to be the "training 1RM". It is a hypothetical number based somewhat on experience but not to be taken too seriously as something that can be reproduced on demand like a scientific result.
But with that being said, since starting 5/3/1 I've come to realize my own most honest answer to your question is "I don't know but I'm enjoying finding out."
Example: After doing the daily dose on 5/3/1 for squats I've found that 5x10 @ 50% makes me "$h1t a kidney" as Wendler would say, and yet I know I can easily do more - more sets, or more reps, or more weight, and probably any 2 of the 3. I'm not used to the endurance stuff, and am now learning the endurance stuff is far more mental - it's about determination. So I might try 5x10 @ 55%, or perhaps 5x12 @ 50%.
I guess I'm saying that I don't know the answer to your question yet because I don't have the experience, but it seems to be another one of those areas where you can enjoy pushing the limit. If you can do 10 @ 50%, can you do 12? Then 15?