I think I can speak for myself in this answer ... Well I'm a bit of a serious guy at what I do, I mean, I'm constantly "playing my odds" by spending more than 12 hours of pure encounters, those more than 12 hours of play allocated to encounters is more likely to get 1 shiny "earlier" than someone who only spends 1 hour to encounters (I hope you can understand my point).
But I agree with you that SRIF.