It's not a great way to see if you've finished memo. For 3BLD, you can start by tracking all the pieces you've memoed using your fingers, and after getting more experienced you can try to do it in your head. For 4BLD/5BLD wings, I literally just go through all the wings quickly and see if there's any wings that I feel like I haven't memoed
But im confused :
E.g. 12 pieces, 2 solved, 2 cycles.
12 - 1 - 2 + 2 = 11
But if I do another cycle to solve those pieces, it becomes :
12 - 1 - 2 + 3 = 12