Depends on several factors:
A) have I eaten yet?
B) am I on my way to get or to the Company after getting food?
C) is it raining still?
D) do I have to go #1 or #2?
E) do I have a paper from an earlier run?
F) is if my partner's paper? Then I'll find you a headless corpse.
G) did I mention food??
Seriously though, I have rarely gone so far as to run plates out front, or run the guy or gal opening the door. 911 hangups is usually one unit and one cover (4 cops total if the cover shows up), but if there is nothing obvious and my hair doesn't stand up, I'm clearing ASAP. Have other stuff to do. Knock knock, you all good? I'm gone.
If something tickled me I'd go deeper. But if a sleepy looking home owner opens up, I say check your phone lines and clear.