Actually, I think of U' M' U2 M U' as a different thing entirely, and not as a setup/cancellation of the M' U2 M U2 commutator. In fact I think more when doing M' U2 M U2 type commutators (in terms of which piece will go where) compared to doing U' M' U2 M U'. I just view U' M' U2 M U' and U M' U2 M U as a V shaped 3-cycle, with the middle 3 moves being the same and the U'/U at the start/end will be in the same direction as how the pieces cycle (ie U' M' U2 M U' cycles DF>UR>UF and vice versa). I find this alg very useful in BLD and it helps reduce thinking a lot if you just think of it as a 3 cycle alg, so really in the case of DF>DR>DL I just see the setup moves as L2 R2.Actually, as I was typing this, it occurred to me that the logical thing was probably to do that. And that's actually how I do it on a 5x5x5 or a 7x7x7, although I generally have to think about it too much (I think of the L2 R2 U' as setup moves, and usually don't do the cancel).