If you don't have a good "hard" drive after those long warmups, you're asking for trouble.
Idling that long will wash the lube oil off the cylinder walls, accelerating normal wear and hastening compression loss. Running at high idle will slow this process down, but not eliminate it entirely.
If you're not driving it hard enough to warm it up within 60 seconds of driving, stop idling it and plug it in overnight. And by "warm it up" I mean to have heat at the registers, which usually means 100 degree (or so) coolant temps.
The "industry accepted" standard is one gallon per hour. Observational evidence on my own Detroit Series-60 engine suggests half that. And the Detroit is a 12-liter engine.
At the current price of $3.50/gal, how much MONEY are you wasting?
Maybe enough to pay for that coat to keep you warm? *snicker*