Map, citadel, anomaly and pinnacle bosses should consistently drop T16 waystones.

I'm not saying that manual corruption has no place in the game, but it shouldn't be the main source of T16s. Considering the fact that T16 is pretty much the only waystones you wanna run in the late game, I'd say that boss drops should cover at least half of your T16 needs. Maybe even more, if you invest into some atlas passives that would boost it. Cause right now the process of upgrading your ws to T16 is atrociously and mindnumbingly boring.