Games should be set at not just 24hr but 18hrs and 12 and 6 (For Freemium).
It is from the Freemium visitors that new Premiums will be made.
Once on site if there is no action they disappear and never come back. Having lower turn setting increases the chance of getting through a few games in those crucial first days.
The longer they hang around and get to familiarize themselves with the site the higher the chance they will be converted to subscription imo.
Just a thought.