I confess this is completely lost on me. If you can lift 100 kg, and a program calls for 90% 1RM, that's 90 kg. If you do 90% of 90kg, then that's 81 kg or 81% of 1RM. So why not just find a program that calls for 81% of 1RM in that situation?I base all my barbell lifting percentages on 90% of my 1RM or my 'training max'. I learned this from the outstanding 'Tactical Barbell' and Wendler's 5/3/1 has the same approach.
-S-