Houston is not Denver. A full compressor blowout every November is usually wasted money. What fails here is the backflow preventer on the one or two nights we drop into the 20s, especially in Spring, Tomball, and The Woodlands.
Before a freeze warning: shut the irrigation isolation valve, open the backflow test cocks, and wrap the device. After the freeze, pressurize slowly and look for cracks. If a zone is dead, that is sprinkler repair, not a reason to replace the whole system. Schedule a freeze check if you would rather not crawl the side yard at 10 p.m.