I have every SR, R and just missing the newest N from the gacha. I was simply much going for the SR cards the way i described previously and just kept clicking specific spots, which eventually also gave me all the other cards. For me, N and R cards seem to show up a bit everywhere, while SR cards have specific spots. Haven't seen a single SR card that wasn't in its own 1-2 designated spots, no exceptions (well, some of them had up to 3 spots, but still).