Below is a timely (yesterday) quote from Steve D'Antonio copied from another forum on this very subject:
"Thu Mar 17, 2016 5:17 am (PDT) . Posted by:
stevedmarine
High revs, 75% load is often more than adequate to achieve the desired ideal temps within the engine, makes good sense for several reasons in addition to soot reduction. Most trawler engines are woefully and chronically under-loaded, which leads to excess soot formation in combustion chambers and in turbos and exhaust systems, as well as wet stacking in some cases. Light loading also leads to overly cool combustion chambers/exhaust gas temperature and "cold" oil. The former, again supports build ups on valves and rings, and the latter leads to sludge and then varnish formation. Thus, a hard, 75% or more load for 10 minutes out of every four hours will serve to stem some of the effect of light loading.
Having said all that, it's best not to do this immediately before shut down. This sort of loading does get things hot, which is good under most circumstances, but not immediately before shut down. Oil that remains on very hot surfaces like turbo shafts and exhaust valve stems after shut sown will undergo a process known as coking or carmelization, the oil essentially bakes onto these surfaces, which can impede oil flow and lubrication in the future.
If you carry out a hard run, be sure to follow it 10 or more minutes of light or no load to allow these regions within the engine to cool off. Often, but not always, that's accounted for by docking time alone.
Steve D'Antonio"