This is how I see it!
If operating on torque limitation at low DA then I'm not close to the engines rated limit when pulling 100% Q so pulling 100% is not causing the engine harm, it's stressing the transmission.
The TOT temp limit is of course there for the engine.
See the engine only produces about 317 hp @ 100% Q which is about 75% engine power. Although most manufacturer's won't tell but its likely that the components were designed to last at least up to 150% TBO and using the 5 min power rating is not really going to make a big change in the overall life expectancy of your engine or gearbox. They are just as likely to fail before TBO if you baby them all their life.
But exceeding limits is another matter entirely, then you are really into the experimental pilot category as well as all pilots flying the machine after you, they just may not know it.
But anyway you are maybe overanalysing this a bit, it's very seldom that you have to use the takeoff limit for more than a few seconds except when slinging, then it's not uncommon that you are in the zone for maybe 2 min especially when hauling beton, usually though the customer wants quick pick-ups and drop-off's. Its expensive to have a helicopter hanging in hover and not hauling stuff around ; )
Operationally this is really not an issue, just use the 5 min power when you need it and it's probably going to be a while until you need it again.
I did my initial B206 check-out at Bell Ft-Worth (91) and this is how I remember they explained this. They would not comment on any cooldown period between periods and they were right, it's really not any issue.
Hope that helps! There is really not a definitive answer as far as I know.