If you run LiPo batteries then you don't want to fully discharge them, it will cause damage. If niMh then just charge them if they won't cause the plug to glow.
Even if the plug glows you will want to make sure the igniter battery doesn't go flat part way through the day so if going to a club or race meet then make sure its charged.
As long as you discharge the niMh here & there then it should be fine for a fair while.