This depends greatly on your TM. The general rule of thumb is that if you are a beginner/intermediate and can't SMASH your 5x10 with FSL, your TM is too high or you have NO heart.
If you are advanced, you just choose the weight that you want to do/have to do. Usually around 50-55% but no higher. This is something I learned from OLY lifters in the 60-70's.
So it's kind of nice to have a litmus test for all the "training max must be SUPER HIGH" people who don't understand how this works.
Case in point - we started kids on Krypteia program with 85% TM. Today, after 9 weeks, all did their TM for 8-20 reps. So we added 15 pounds to their TM and added 3-15 reps.
Yes, this works. Yes, the program kicks ass if you are willing to work.