Looking back on my own childhood, it has become obvious to me how schools, of any description, are utterly incapable of supporting even those with mild autism. During my school years, I was melting down violently at least every few days, sometimes even multiple times in the same day. But in the 5 years since leaving school, I have not experienced any meltdowns at all.
The forceful nature of schools are detrimental to people on the spectrum. Most of my own meltdowns were caused by being forced to write by hand (something I cannot physically do), and the forceful intermixing of many utterly unrated subjects. I, like most autistics learn best when I am able to focus on one thing at a time, and that one thing is something I am passionately interested in.
So if your autistic child is frequently melting down in school, or if you frequently melt down in school yourself. The very design of the school system could very well be the root of the problem.