I'm noticing a significant fluctuation in shorter blocks. On the order of ~30% smaller rewards only on shorter blocks, but not all of them. I don't know if these are miscalculations or if people are getting lucky with some sort of pool hopping guesswork
This would be normal if your hash rate is rather low (less than 100-200MH/s). At about 1GH the variation for me is usually less than 10% (short or bonus).
In essence - it has to do with the way this pool pays rewards - the reward is based on the score, and score decreases exponentially with older shares. If you manage to submit shares in the last second when the block is found - your score will be the highest (for those shares) and you may get extra few %, and vice versa - if your last share is over a minute older when the block is found - that share would bring you a lower %.
I understand how the pool calculates rewards, but since I'm hashing along at ~ 700MH/s, I would assume there'd be a smaller variance than 30% over the course of 45 min to 2 hours. the 4 hour blocks match up with the average of 1-2 hour blocks, excluding these outliers but if others aren't seeing them, it must be something on my end