KDOC Anaheim-Los Angeles has aired Perry Mason every Weekday at noon for at least the last 20-plus years. For awhile, several years ago, KTTV would air Perry Mason (concurrently with KDOC) most overnights. KCAL, for years, aired the made-for-TV movies every Saturday night.
I'm not old enough to remember, but I can't recall aired Mason reruns locally prior to KDOC.