You need to have a record when you apply for a rating/cert (8710), or if you need to prove currency.

Basically if you are flying, you must be able to prove that you have met all required currency...at a minimum this is a BFR, but might include landings, IFR, type, etc.

Since you do not have to carry your logbook with you while flying, I suppose you would be OK as long as you updated it before handing it over to the feds upon their request.

The risk is that if you are in a serious accident and they cannot find your currency in your logbook, you might get blamed for being out of currency.

Also you do not have to log all your flying...many old-time GA folks just log what's needed to show currency (for the feds and insurance).