Tell me if this is crazy but I think I've realized something great
If we use BTR-esque setup, we can reduce ZZ-C's OLS set from 501 possibly down to 128 or less.
Basically if we set the cube up so that a U layer edge and an oriented corner are placed BTR style, you have 8 OCLL cases. From there, the edge can be in 1 of 4 places and the corner in 1 of 4 cases. 8*4*4=128
By recognizing the OCLL and the location of the F2L pair pieces, you can perform 1 alg that will orient all corners properly and solve the pair in such a way that when you fix F2L your OLL is completely done!
Here are some examples for those who are confused. It's a hard concept to write but it's actually quite simple once you see it.
EXAMPLE 1
EXAMPLE 2
EXAMPLE 3
This can be made even more crazy if you learn it so that you only need a U layer edge for BTR setup (corner doesn't matter.) Even here, you still have less algs than with normal ZZ-C, giving 128*4=384
This can also be applied to ZZCT, with any corner and a U layer edge being placed in back and using 1 of 32 algs for TSLE. If the corner orientation doesn't matter, 32*3=96 in comparison to the normal 104 (so maybe not entirely worth it to use twisted corner)
EDIT: Typed in the wrong number. 128*3=384, not 128*4. Also these stats have some variance due to symmetry. May be more or less than those given here.