Perhaps once in a specified amount of time. Every two weeks? Sometimes I forget things and a reminder isn't inappropriate. Spread over all channels if possible, rather than once per channel per period.
Also rather than silently skipping, perhaps a couple of seconds pause with “sponsor segment for <product> skipped” displayed, at least as a default the individual users can switch off.
Perhaps once in a specified amount of time. Every two weeks? Sometimes I forget things and a reminder isn't inappropriate. Spread over all channels if possible, rather than once per channel per period.
Also rather than silently skipping, perhaps a couple of seconds pause with “sponsor segment for <product> skipped” displayed, at least as a default the individual users can switch off.