My brother used to work in a bar and asserts the following:

Some days he would work all day and see people put money in a machine and not win anything much (e.g. jackpot never came up). Believing that the machine had a payback rate that would balance out over a few hours/days, he would deliberately put a bit of money in at the end of the 'no winner days', and would often win enough that it made it worthwhile overall.

Anecdotal, but it seems consistent with your understanding and is a source of an edge.