Is there a minimum break they need to take (or rather could the downtimes be shorter)? UK has similar rules for contracted people.It is actually due to contractual / legal reasons. Not even because it’s cheaper.
In France, you cannot have a fixed term contract for an open-ended job. In other words, if the shows were running year long without any breaks, Disney would have to offer permanent contracts to its performers. It would therefore impede them from refreshing the cast or even replace shows by new ones.