From a different view that would mean only 3 working sets in a sense. Since those 2 percentages are of my WORKING weight, I'm using percentages of my 1rm, somewhere factoring in 90% (3RM) whether it be the last set or the 3rd set. I did today 80 83 86 88 then 90 and crushed my 90% set, with double the reps. It worked well, but also thinking if I wanted to do like 1 set, 2 set, then for the last 3 I would do 90% 1RM.. The first set would be 80 or 83% of max and the second would be 86 or 88%, pretty much asking what other people would do for those, or if they would do it the way I did it today. Doing it the way you said BTB just seems like too big of jumps in weight, but when I was all warmed up today they weight felt like butter and absolutely felt strong as an ox.
"You will do well. The beauty of being your age is that it is difficult to overtrain." -jesseisrael