Honestly each person finds out what works for them. If you are happy you will last. It sounds as if your service is to busy for long shifts. Becoming tired and frustrated may lead to burn out. In my case I work long shifts used to work 14-24's on 7-24's off for 2 years, but we averaged 2 calls a day or about 8 hours in the ambulance per day. So we got rest. That still started to take the joy away from me. Now I work at my full time job about 8,9 24's evey 28 days. If I decide I want to work I do 2 or 3 24's a month at my part time. I now have fun again as I still have plenty of time for me and my family.