Optimal hash setting choices for a mobile app

[adams161]

With default Stockfish it starts up with 16 Megs of hash and apps can let users set their own value. I've been wondering whats optimal here. In OpeningTree for android that i released with Stockfish, I went with choices from 8-512.

Now Stockfish when you launch it prints "1option name Hash type spin default 16 min 1 max 2048". Now I noticed that Chess - Analyze This allows a 4096MB setting which is outside the allowable range.

Now on mobile it seems you might want to be a little conservative on memory as the mobile devices run out of memory faster. But the greater issue i wonder about is for a mobile environment were you might run an engine to look at something for in my view no longer than 15 minutes due to battery or being on mobile not a desktop, how much hash can the engine really use? It seems with 1024 megs of hash you'd need to be crunching over night to get the benefit.

thoughts?