"So, the school shuts down the heat on weekends?"
Yes, our thermostats are set back for weekends and evenings. We can override for events, but if there are no events the temp is down. Isn't this the fiscally responsible thing to do?

"There is occupancy expenses but that is a lame issue-"
Seriously? You obviously do not have a clue as to what it costs to maintain/heat a space like a 2200 seat gymnasium with exterior doors opening and closing or what it costs to operate such a facility with lights, water, toilets flushing, etc.

"Mill Valley Kids Tournament - 800+ wrestlers
High School Regionals - 112 wrestlers (5A/6A)"
Unclear as the point you are making Chief. Both events are expenses to the district. The question I would ask is what portion of the expenses for the use of the facility, equipment, etc. are reimbursed to the DeSoto school district? Here in Norton we have charged nothing for our local kids club to use the gym and nothing for the use of our wrestling room, mats, scales, locker rooms, etc. etc. I think this is as it should be. BUT, these things may become more expensive for clubs. School budgets are set in July/August and when costs increase (as our local utility rates did last month) and/or funding decreases (as has happened five times already this year) something has to give.