Mining is just like tossing a coin: head is a share, and tail is not a share. You will expect 1000 heads out of 2000 tosses, but at the end you most likely will have something not 1000 and close to 1000.
But lets say I have 100mhash, according my calculations it should be about 85shares/hour.
So regardless how lucky, I will always get 85shares ignoring stales and network problems?
So this means one day is 24*85shares= 2040shares.
On a PPS pool before fees I get about 0.05bitcoins/day.
So ignoring fees after 20days I would have mined 1BTC and the share is solid at 85shares/hour ignoring stales and network problems?