FM and IM have a wide range when you're talking about work hours, rotations, opportunities etc.
FM at my hospital doesn't even rotate through the ICU and its mostly clinic. Outside of the couple months on floors its mostly 9-5 work. Meanwhile the FM at my medical school spent a month on trauma surgery, another month on MICU and Q4 call when on the floors.
If you want a relaxed 9-5 lifestyle theres more programs that have it in FM. But you gotta do your research. Every program is not like that. Some FM programs are focused on OBGYN or basically training hospitalists.