A standard at our club is for a standard battery pack is for 6 ten minute flights and then pack it up. This is flying time from takeoff to landing which doesn't include engine start time, engine adjust time and taxiing to and from the runway. This will also allow a safety margin. We have found that 60 minutes flying time in 1 day is also plenty for a new flyer. More than that and they seem to start to lose concentration. Some new flyers can't handle more than 3 flights before they are burn't out!