I use this typical workout 2x a week with my boys and 2x with myself ( the other 2 are the FSP and FBE by themselves to 60s with rest cycles ).
In any case. Typically, some of my boys only do FL/BL negatives instead of the holds since they will hit that point and generally fall out. They haven't figured out when and how to squeeze though I will help them if I can with some spotting (if I'm free).
Lately, with some of the boys, I would like for them to master the basic body lever. If we have time, we can work these after the 3 embedded sets but time is short typically.
I have been thinking about having them do 1 tuck FL negative and/or then 10s of body lever on the ground+ the corresponding core FBE. Or what about switching the BL hold with a BL negative (in case I'm spotting something else or watching their planche work). Perhaps instead of body lever on floor (using the base of a Balance Beam) doing it on a single rail once they have mastered the basic candlestick on floor (doing it on a single rail would be good for back hip circle and the basic undershoot).
It just occurred to I use a modified order of PL, BL, then FL vs BL, PL, FL because I need to hit the PL earlier regarding freshness. I played around with rest cycles and found it still best for myself to hit the PL first rather than 2nd. Then again BL, isn't really a weakness of mine. I actually played with putting FL 2nd and BL 3rd but it didn't make FL any easier really and the BL stuff definitely was tougher.
As well, my boys frogstands are still very infantile, so I usually couple frogstand work with a planche lean on a floor bar. We jokingly say nipples at least but go for the belly button.