it does sometime, but at the end, the total coin will be approximately the same as expected.
I sometime during the nice hash, I switch to other coin and come back.
Well, it's been happening to me for a few days in a row, so I eventually just gave up and switched to Bitcore. Been getting more from mining BTX than from Smartcash before. I also tried mining smartcash solo, but didn't have much luck for some reason. Spent 3 or 4 days on that and got a lot less coins than I was getting from the pool before. Could've been luck, I don't know..