just some points to consider:

* under load (i.e., in a higher gear, lower engine rpm), more heat is transferred from the combustion charge to the engine.

* a higher engine rpm (i.e, driving one gear lower than usual) sends more oil through the engine, fulfilling its lubrication, cooling and cleansing functions better. The coolant also flows faster.

* when you do your italian tuneup on the highway vs in neutral on your driveway, you get more efficient engine cooling

* prolonged driving at elevated rpms also clears the condensates in the exhaust system (which are acidic)

but the best point is that these engines were meant to be driven this way, and they can sustain those conditions indefinitely ...