I never let my car warm up. I park my car in an attached garage and don't deal with scraping windows.
Regardless if it sits out at work and it's 8F, I start and immediately drive gently until it's warmed up. Letting your car sit around and warm up causes fuel dilution which isn't an ideal lubricant. Look at UOA's with high fuel dilution and the higher wear numbers that often go with it.
I've owned my WRX since new, long been stage 2 and has 118k miles of trouble free service.