If users had the option of disabling automatic sync, they could run a manual sync instead. (Which I think is currently possible anyway). For many users this might cut down dramatically on useless strava API calls.
In exchange for enabling this feature, the manual syncs could be higher priority. (And subject to a limit, e.g. say 5 per week?)
Similarly, you could prioritize manual + supporter syncs even higher.
Just another idea for reducing pointless API calls.