For me, the 24/48 is the worst possible schedule to run, because it's essentially a long death slog of work, recovery and preparation and it is an excuse to literally consume at least 33% of someone's life for average pay at best. A 48/96 is actually preferable to me because it front-loads all of that time into a manageable block of time and still gives three functional days off, but you've got to balance fatigue and UHU against this convenience. For somewhere like Colorado County, TX or the I-10 corridor? It makes plenty of sense. Low volume, long trips, a distributed workforce that has to drive a lot to get into work? Perfect sense. For someplace like Fort Bend County, with a population pushing 1 million and an EMS system build for 600k? Madness.
12s, on the other hand, aren't perfect either. For one, the push to 12s is a step towards SSM, which chews people up and sets a tone of "meat in the seat". It is possible to make 12s attractive, challenging, educational and fun, but it takes a lot of work, and it makes those shifts more expensive in terms of everything from salary to maintenance. If you want to see this in action, look at MedicWest in Las Vegas- AMR seems to have managed to go a long way towards extinguishing what made shifts fun and they're starting to founder if Facebook is to be believed. Second, for rural places, 12s suck for a lot of employees if they're commuting in and leads to cumulative fatigue, especially if a late call is tossed in.