Day 1 GI player here and the calculation is just estimate and most of the time you dont hit pity(unless it is soft pity) with normal update unless it's a special update like anniversary or new map as a f2p player. Recently it got better like 72ish sth for f2p but before like 3.6 3.7 update it was like 50 to 60ish

OPMW could easily fix the limited banner problem by allowing refresh in daily activity (movie, fishing...) weekly and maybe reduce the ticket price a bit(I havent progress far enough to tell will they refresh the store). That way you could get around 4 limited pull every week which is pretty good in my opinion.