It depends on how often you use your mobility scooter but, as a general rule, you should charge your batteries after every use. So once you get home or have a break its best to charge your batteries. All shop riders and mobility scooter work off the same batteries so this will apply to all mobility scooters.
The general rule of thumb is not to run deplete the mobility scooter batteries completely.
All mobility scooters and shop riders run on the same batteries, sealed lead acid batteries. This means that running the batteries completely flat and then storing it while flat will lead to the batteries not being able to regenerate their charge. Which will mean spending money on replacement batteries. The big ones don’t come cheap.
So, don’t leave your batteries flat and charge them after every ride.