My formal policy is a space is a space in my program - if you are not paying for it than I will enroll someone who is ... aka you withdrawal or drop down in summer your full time space might not be there come SEPT
I have peers who charge teachers more each week September to June and keep a deposit over summer to return in September - if they bail they loose the deposit but the provider got premium fees from Sept to June to cover no fees for July and August and they had benefit of quieter days to boot...some of them are teacher only programs so they are actually closed July and August and others are normal programs who just offer this option.
I empathize with teachers child care challenges however I am not taking a hit in pay for the pleasure of serving them when there is a demand for other needing full time care.