85% of the time I show up to unlock someone's house for them it's because the door accidentally swung shut and the keyed doorknob was unknowingly locked. This is why I recommend passage doorknobs on all of your entry doors. That way there's no way for the door to get locked unless you locked it with a key from the outside of the door. Most people think the added lock on the doorknob provides extra security, but the truth is that they don't. The reason is in the design of the spring loaded "dead latch" that all doorknobs use. Ever look close at the latch? You'll probably see a second smaller latch that moves independently from the bigger one. That smaller one is supposed to be held back by the strike plate, and when it's installed and working properly, the latch won't spring back anymore when you push on it, making it almost impossible to jimmy the door open with the old credit card trick. But there's a big problem... WEATHER STRIPPING! It's squishy and you can almost always just push or pull the door shut harder with will allow the little latch to extend, now making it very possible, and probably pretty easy to jimmy it open.
The point I'm making here is that even though people get locked out of them all the time, they are not actually providing any extra security to your doors. It's just more locks to rekey or service in the future and more potential for you to accidentally get locked out. The whole point of knobs with spring loaded latches is to keep the door shut, not to secure the house. I recommend to all of my customers to replace the keyed knob with a "passage" or "hall & closet" function knob or lever on all of their entry doors and let the keyed and blind deadbolts do the securing.