All coins make the same amount of profit per day. People use monitors that monitor profitability and they switch to the most profitable coin to make an extra %'s.
No secret to this. Unless the coin is unlisted and then nobody mines it, but that's a gamble.
There is some truth to that, but a lot of the small market cap coins DO fly enough under the radar to have periods of time they make a lot more (or a lot LESS) than the "basket of profitable coins".
DGB spent a couple of weeks outperforming everything else before folks started talking widely about "mining skein", as one example but even then it took a good week to drop back into the range of the basket coins.
Quite a few coins that bounce around a lot on price too, like lbry and at least one lyra2rev2 based coin, where if you wait for the price peaks you can make quite a bit more semi-consistantly than otherwise.