>>529225690
the average payout for 0.6% is 167 rolls.
in 160 rolls the devs will give you 2 payouts, statistically 1 of which will be the banner.

thus is 160 rolls, you will get
+ 1 (useless) S rank
+ 1 banner S rank
+ 1 statistical drop

thus the average drop (for useful things) is about 81.
and for all total it's 160/3= 53 rolls for "anything S"