I also am a fan and bought the 2nd edition 5/3/1 and the new "Beyond 5/3/1". I think I made the same mistake? I've been doing what I thought was the base program plus Joker Sets and FSL and BBB assistance plus various other things like pull-ups.
Yesterday was deadlifts: I did the 10% x 5, 20% x 5, etc until 70% x 3, 80% x 3, 90% x 1, 100% x 1 (only managed 1 that day), 1 joker set, then 70% for 3 x 8.
Then I did squats for 5 x 10 at 55%. I wondered if I was implementing this wrong as my workouts have been getting pretty long.
In those early sets where the recommendation is say 3-5 reps, should I always go for 5? Or go lighter so I have more available for the heavier sets? Or should that decision be a function of how I'm feeling that day?
So adding BBB assistance to this appears to be to much, what are some of the rest of you doing for assistance work while doing the Beyond 5/3/1 base program plus Jokers and FSL?