My boss in Tampa swore by using a 22/2 wire for all zone runs, even for contacts.
He said it was cheaper and easier to stock one type. I did that for a year until a job with a 200 foot run to a garage door contact gave me constant false alarms. The voltage drop on the long run with that thin wire was the issue. Switched to 18/2 for anything over 50 feet and the problems stopped. Anyone else run into trouble with using the same gauge for everything?