In theory the luck should be the same for all over time. The difference comes down to % of the total reward shared - fees. One thing I have noticed if I'm not wrong is that we are on the cusp of becoming a pool that doesn't expect a block every retarget period. I think right now we expect 1 every ~16 days. Given we have some transient hashrate we seem to swing above and below that right now, hopefully we can attract some more permanent hash.