At my last job I was on a 48 hour shift in a rural town. Problem is, we would get sucked into the city if levels were low.
Everyone loved their 48 hour schedule, but you worked hard and got little sleep. But sometimes it was very slow. Maybe 2-4 calls in 48. Others it was non stop.
In the month before I left I had two shifts where we got 6 hours of interupted sleep for the whole 48. During one shift we were running calls for 40 consecutive hours. This was a time when we were at critical staffing levels. Crews were calling their supervisors pleading for mercy. My supervisor put one of the crews out of service for sleep, something that is not a policy at the company. Before they got back to the station a manager (from home) vetoed the decision and put them back in service. The supervisor put them back out of service and told the manager "you can keep putting them back in service and I'll keep taking them out. No one is getting hurt on my watch, and if they do, it's on you." They never got sleep, and were held over 6 hours that day, only allowed to go home when the EMT said he had no child care coverage. He doesn't have any kids.
I don't have a problem with 24s and 48s. But it needs to be supported by responsible management.