> It seems like the monkey's-paw curse for this kind of legislation is to show several ads in a row, each allowing you to skip them after 5 seconds.

As is often the case I think that means the restrictions should just get even more strict, e.g., "no ad may ever be longer than X seconds and no app may ever show more than Y seconds of total ads within any 24-hour period". Then add some extra clause like "any attempt to circumvent or subvert these rules is punishable by fines up to 10x the company's gross annual revenue, plus asset forfeiture and prison for executives". People at companies should be deathly afraid of ever accidentally crossing the line into abusive behavior.