Thanks to Dave and Jay I did my first endurance race last year - It was probably the best thing I could have done to improve my riding ability, learn the track and work on body position, braking points etc
You can work on different things since you don't have to go all balls out all the time like in a race, do 5 laps working on braking points, then take a couple of laps as a bit of a break, then work on something else if you wish or just go all balls out for another 5 laps
However, you better be prepared, it's called endurance for a reason, 40 laps in a row is not easy and you are still racing so you are expected to maintain certain pace