Yeah, no.
But to answer your actual point, on the Expressway, especially southbound through the city, a lot of lanes are de facto exit lanes and you need to commit to one and slow down to exit well before you leave the highway. A lot of exits also feature sharp curves and confusing merges.
...except I lost count how many times I saw ambulances driving code 3 Northbound on the 93 as far South as Neponset Circle (I lived in North Quincy for a year)... and being passed. Can you justify driving lights and sirens and being passed that far South from Boston? I certainly can't.
I also don't think a responding ambulance needs to be moving faster than all traffic, and I think buying into that idea leads to a lot of dangerous driving.
If you're being passed by the majority of traffic, then what's wrong with the idea of downgrading to code 2 until off the freeway? It's not light the lights, sirens, privileges are doing anything useful (oh, no, you're "speeding," along with 90% of the rest of the cars on the road. L/S doesn't change the safety of speeding, only the legality... which is de facto legal). Buying into the idea that once the lights on, they can't be turned off is dangerous.
Besides, the driver of a responding ambulance is already task saturated; the last thing they need to be doing is thinking about whether they should have the lights on.
If the ability to judge whether the lights and sirens are doing something useful or just being a liability is too much, than the driver is too stupid and incompetent to be performing such a dangerous task. It's really not that hard. "Can I get through this light without pushing 5 cars through the intersection against the red light? If no, turn off L/S and wait." "Are 90% of the cars on the freeway passing me? If you, turn off L/S. Turn back on when situation changes or I'm exiting the freeway."
If simple things like that are too much to ask, than EMS is really beyond the realm of all hope.
An incompetent attendant is a danger to the patient only. An incompetent driver is a danger to the patient, the attendant, the driver, and the general public.