Finish learning COLL, since you're almost there anyway.
With WV, it's worth knowing about a third of it (and be able to mirror to the back) but I don't think knowing the whole of WV is worth the effort.
Everyone should at the very least be able to recognise when to do U R U2 R' instead of R U' R'. It's also helpful to be able to recognise other Sune cancellations like R U R' U' R U' R' and U R U' R' U R U2 R'. There's the case with everything except the pair oriented, L' U2 R U R' U2 L, which is so easy to recognise. Lastly there are cases like U' L' U R U' M' x' and R2 U' L' U R' U' M' x' and R2 D R' U' R D' R2 which are quite short and easy, especially if you think of them as 2 move setups to a normal insert.