We lock our doors but it's completely unnecessary IMO.
I'm up all night most of the time and sleep some of the day. My wife sleeps at night and is up during the day.
We have dogs that are such sissies that they could only be a security benefit by barking. If you pet them quickly they might not even bark at all.
There are very few "strangers" in this neighborhood and I've not heard of any thefts. Violent crime here is low but normally theft is high. But not here.
We have a working car but like most people here don't use it much. Sometimes I creep inside and get very quiet to act like we're not home when we are.
Even then the door is locked.