Benefit of leaving the truck plugged in when the weather is cold?

What I see on my Lightning using a JuiceBox EVSE is that overnight it will briefly draw a few kW for a minute or two every few hours from the wall, presumably to warm the battery pack a little.
I don’t know what happens if you’re unplugged but it’s either that it’ll use its own battery to do the same or it won’t try to warm the battery pack as much / at all.

MCM said:

Does it help or hurt to precondition your cabin when you are not plugged in? You just finished your meal at a restaurant, and it is 20 degrees outside, and you want to drive away in a warm truck????

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In most cases it ultimately consumes more range to precondition off your battery pack versus just stepping into your cold truck and driving off. In fact the same is often true about Departure Time conditioning — you end up using more shore power than what you save in battery capacity.
The main exception I can think of is if your battery pack is discharged enough for regenerative braking and you have a steep downhill initial leg of your drive (think: ski vacation, leaving your hotel).

Otherwise it’s mostly about your comfort, how long you need the battery pack to last for your trip (like if you need to go 180 miles and a cold pack would only go 160 but a preconditioned one can go 220, it arguably saves you a charging stop).

For me, I don’t precondition using shore power in cold weather unless I need the max range. The reason is my winter off peak ends at 7AM and then electricity is 75% more expensive!

Art p said:

I did notice this week after three days of not driving I lost about 2 percent of the charge. Temps at night here are going into the mid 20s and I park outside because the truck won't fit into the garage.

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I also park outside and especially on days when it’s actively snowing, I leave it unplugged so that our driveway plowing service doesn’t accidentally run over the cable, etc. the drain is actually fairly minimal compared to our Teslas.