One of the reasons for the L-sit mastery is to make sure you are strong enough to maintain the position for tuck, adv tuck, straddle, etc as you train for the harder versions of the planche.
As for your main question, ask Steven Low.
Considering we trained from 4(30)-7(30), we had to have some form of break to eat. It also gives them a bit of downtime to just relax for 7-10 minutes. We're talking about young boys here. You have to figure it would have been 2-3 hours since they had a snack so they usually were getting hungry since it was around 530-6.
Some coaches do not allow their gymnasts to have breaks and instead keep their snacks in their lockers. However, they end up burning just as much time and I've had to shoo kids away from the junk food machines in the gyms or come across the fact of what they would keep in their lockers to snack in was not what I would approve of.