Debating a Pan Heater along with block. Need some advice here.

Should I? The block heater does decently at -20C, of course, but the car is parked outside and on windy days I feel like a bit more heat really wouldn't hurt.

Thoughts? Most affordable pan heater?

Also at what temperature at night should I increase my 1.5 hour heat cycle to 2, or 2.5? 1.5 hours seems to do the trick now at freezing, just not sure how long the rest of us run them for...

We just use the cartridge block heaters in ours here. All plugs are on a timer so most are powered up for 2-3hrs max which is more than enough time in my opinion. Haven't had a problem starting anything so far. I've replaced more drivers seats than batteries.