" The other way to do it is to trust our guts on the matter. "
Yes, that's seems the best way forward. All this talk of calibration is getting too deep for me; and, you know, some people like timers, me included. Sometimes. Depends how they're implemented. it doesn't help that I'm a hypocrite. I don't like all the F2P malarkey, but my last 3 purchases were all IAP. (Extra tribe, ad removal and MMO energy). If I want to support a developer and that's the only choice then so be it.