I find the opposite to be true, and manufactures for new cars with AGM tell you to disconnect them if car will sit for 2 weeks or so.

The Lead Acid Interstate in my 70 RR never needs a charge and works great. The AGM and Resto battery, will not hold charges if left too long, especially with a small drain, like a clock.

I believe even Modern Optima techs state occasional recharge with correct charger required.