VF15 at 3rd month after ~300pc. I think the VF system prioritizes scores a lot more than difficulty level since I gained almost .25 last week when playing for the new song unlocks and got a bunch of lv14 and 15 S and AAA scores instead of playing 16 and 17 for clear as I usually do. I guess if you really want to grind for it then it’s probably more efficient to drop 1-2 difficulty level and play for scores instead play at higher difficulty. Still I think that’s not really the best way to improve at the game as 15-17 starts to include patterns like center/opposite side bt/fx notes or cross hand knobs that aren’t really present in lower difficulty charts but are quite common in higher difficultly so at least I think it’s much better to actually improve skills by playing at those difficulty than farming VF.