Help with battery calculations

Hello I have a bunch of old parts laying around, and am planning to build a small RC car.

Specifically, I have a BL3650 motor along with a 120A ESC, a RX/TX kit and a few 5200mAh S2 C50 batteries.

What I cannot understand is how to calculate the duration of the battery.

I guess the ESC is not really drawing in 120A, since the motor is rated for 56A peak, but I can't find anywhere what would be an average absorption.

Can you suggest a practical way to estimate the battery duration?

Since I feel the motor would be way too powerful for the intended scope, is there a way to limit the ESC power output?

Thanks to anyone who can help.