Nobody much knocks on our door. Ever.
Used to be bothered by the religion salesmen occasionally, but they don't come by anymore since I fenced in the front yard so the dogs can cover both the front and back door now. (I'm with shooter1, lol 5ft fences and Chow dog)
Relatives know to call. My sister in law walked in without knocking ONCE and figured out really quick that we don't keep useless lapdogs around here (like she does)
So yeah, I'd be really suspicious if somebody knocked, especially at odd hours.
However, I have no qualms about going places and being outside after dark. I walk my dogs after dark a lot in the summertime (it's the ONLY time to be outside!) Course the dogs generally keep the creeps away, and if they don't well.....