It's been long know that maintenance (as well as preventing some problems) causes problems, hence the introduction of on-wear or on-failure maintenance, especially for redundant parts (like magnetos) and delicate parts (like avionics).
I'd be much more concerned about single vacuum failure on a dark and cloudy night, than a magneto problem.
There's only so much money to go around (remember affordable safety) so we should be spending it to get good benefit, not arse covering,