Depends what you mean by "supervise" ...
If you mean sign the charts and drink coffee while the CRNAs run wild and do their own thing, yes, in time you will be a pathetic pale shadow of what you were because you're not actually doing anything.
If you mean see all the patients in preop, and in PACU, and do all the blocks lines epidurals ?TEE, and are present for every induction and every emergence, and handle consults from whoever's screening preops before DOS, and get to the OR for critical events or complex patients, then you are likely to gain experience 4x as fast if you're supervising 4:1.