No harm, no fowl. A system not shutting off for a couple days when it's 100° and 90% humidity is efficient. If it cycles on and off every 20 min. under those conditions it is over sized. I wholeheartedly agree, if it runs constantly there's a problem. If the system doesn't cool it is either low on freon or has plugged evaporator and/or condenser cores. If the compressor is noisy it may need replaced which could cause loss of cooling as well. I had the HVAC replaced in our rental house and they oversized the A/C. It does short cycle and it is cool but clammy and not comfortable inside. Just saying.