After i readed this tread i started to play with kurito.
Till now i used 15 r-gacha tickets, each try one ticket and i got allready the N and R Card,
in my oponion a good way to farm, beside the try to get the cards ,almost every try gives an sr wild 3 card.
Good way for me to prepare the lvling of the slayer cards

If you got all limmed girls I would wait untill the limmed girls change. After the first 3-4 months with the same girls the girls started to change every month. Collecting 300-400 R-Gacha takes time...

If you just want level for you SR girls donating 1x R-Gacha give on average give 2.5 SR level.

Ing:
R.Gachax3
Pero.Puddingx2

Silver:2hrs

Result:
Peronaminx1
Peronamin.Halfx1

speaking of bad luck...

Any tip for the limited N ? I tried it for a month and still haven't got it yet. I keep playing with R-ticket and I got SR-3 WC mostly 90% of all time.