Interstatials - what interval?

in what interval do you show interstatials? - I show an interstatial at start and then once in a minute. I have a CTR at about 1.5%. But there are some users complaining about ‘spam’. What interval did you choose?


I believe 10-15 minutes is reasonable.

For my mediocre apps:
1 on launch + 1 on exit.

For my best apps:
1 on launch + 1 during use + 1 on exit.

For my games (generally):
Every other level completion and one on exit. This should vary between games quite largely depending on genre and level lengths etc.