Stu,
A slightly different perspective on your question.
From the airport operator's point of view, we design the turnoffs from the runway to be conveniently located to minimise the time that aircraft spend occupying the runway. We ask crews to plan the exit they are going to use and adjust braking accordingly. Of course this varies with conditions; headwind, runway state, landing mass (and hence speed). Very few aircraft need to use full power on reverse thrust. The major turnoff on 26L at LGW is designed to be taken at 60kt and the locally based crews will aim to be doing that as they start the turn from the centreline. If the reversers are still open then, it will be at idle.
The very worst thing crews can do is to come to a screaming halt and just miss an earlier turn, then have to apply power and dawdle up to the next turn. This can easily cause the next a/c to have to go around.
We had a 747-100 land some while ago and start the turnoff with a high power setting and the reversers still open. As the aircraft slowed, the hot gases being pushed forward started to be ingested and a thermal runaway occured. 2 engines caught light, pax down the chutes, broken ankles etc. Runway was blocked for a couple of hours. Thanks, guys.
I guess each type will come with appropriate warnings as to how reversers should be used. Of course, we've the luxury of a long runway. If LDA is limiting, then of course max retardation is required.
Another point is an environmental one. Because of our excess LDA we do ask crews to be economical with the use of reverse thrust during the night period, so as not to wake up the neighbours.
Cheers,
The OddOne