How often can you go out of your diet?

Depends where you're at right now.

If you're <10% bodyfat you can actually get away with more regular cheating on diet, like every 2-3 days.

Mostly because when you're lean nutrient partitioning is much better.

If you're 20%+ bodyfat, you can't really get away with regular cheating, maybe once every 2-4 weeks.

If you're overweight and greater than 15% BF, NEVER, you fat sack of shit.

As often as you want. It's your life.