I try to look for advantage play situations. Recently I tried pursuing slot machines that actually give some indication of how close you are to getting a bonus round or jackpot - generically referred to as must hit by slots. I have managed to find and play a number of these and I am unimpressed with their performance.
The true must hit by slots have a counter that consistently moves up as you wager ... but it is very slow ... so thousands might be spent getting a few hundred dollar jackpot ... it is only truly advantageous when it is close to the top ... which one is unlikely to find.
The pseudo- must hit by slots have a count, but they are inconsistent and one could be left waiting a very long time to collect each item that is part of the count ... in essence, you know you are closer to a bonus or jackpot than if you started at the beginning, but you cannot tell just how close you are. These have the further disadvantage that they seem to be low denomination slots with smaller prizes. Even worse, rather than finding these in an advantage state, sometimes you find they are partway through a series and a person recognized they were losing and stopped playing so it is in a disadvantaged state and no one wants to finish it.
It might be worth mentioning there are many false imitations of must hit by slots called persistence machines where something builds up and looks like you are closer to a jackpot when the graphics have nothing to do with it ... they are just there to keep you playing longer.
Does finding a slot left in an advantageous state happen? yes ... and I have won a little money this way ... but at least so far it has been nothing to get excited about. Advantage play at the tables is much more reliable.