Do "New Slots" pay out better initially?

[mingorama]

Does anyone know about casinos tweaking newly released games to pay out better initially, to try and lure in players, before being cut back to pay out less? Two cases in point:

1) The linked Monopoly "Big Event" games, when initially released in casinos --- the bonus events triggered rather frequently, and I enjoyed several winning sessions. After a few months, the frequency of the bonus events seems to have been cut in half, making the game worthless to play.

2) Another linked slot called "Cash Fever". In this Bonus game, you win free slot spins, and based on the number of credits you collect, you reach tiers with progressive payouts (as well as the credits earned with the free spins). Funny thing about this one is that the actual payouts for combinations on the free spins is now HALF what it was initially, making it twice as difficult to reach the tiers.

Anyone have any knowledge of this kind of thing? I'm wondering if it would make sense for a slot player to exclusively stick to "new" games, and switch frequently. Of course, my sample size is very small, and I'm not an avid slot player, but have noticed these things.