Note any allowance/policy would entail enforcement and a tug of war. but see my blogpost on sunk tcost, .. and my evils blogpost.

Therefore, this would not be my base_camp.

==== After I return the iPhone8 to him:
If boy is caught looking at phone screen for more than 30m a day including gaming minutes, then lose the phone for a day, longer if repeated.

gaming … use mom’s phone.

— Boy’s proposal: Once boy is caught taking the phone out without both parents’ knowledge, then dad has the right to lock up the phone in office for up to 52 weeks.
Boy is putting his reputation (honor) on the line — 军令状. Boy believes in his self-control. Boy believes he can resist the temptation to break his promise and bring the phone out.

Judge is mom. Boy also believes mom and dad will be fair.

— Dad’s follow-up proposal:
The phone will have discourse + whitelisted games only

Once boy is caught installing any unauthorized game, same penalties apply.

— timeline:
First complete the Whiplash 1M penalty + any other penalties.
— How the allowance can be adjusted
All three parties agree on an allowance. Mom is the #1 enforcer, controller and judge. Once I catch blatant violations, I will take the phone to office for 2 days, then reduce the allowance, towards zero i.e. lock up for a 3M.

Of course, positive evidence of self-management “earns” higher allowance.