I feel like you can see the difference from casino to casino if playing the same game. I'll notice a bonus hits more often on xxx site vs another. I could be complately fucked in the head and just be seeing what I want to see, but i'm pretty sure casinos can request different rtps.
Different casinos have different RTP, you`re right, but the difference is small enough to feel it if you gambling less than a month i think. And it is possible that in one casino you feel that you win more often than in another but i think that the most times it is just luck and when you`d gamble for a month - you`d not see any difference if RTP in these casinos is the same.