I did hear neighbors in other units, voices, footsteps. In the past people have mistakenly come to my apartment looking for other tenants. But this was the first time someone tried turning the doorknob plus they did not respond when I yelled "Who's there?".
I switched to a pharmacy that does home delivery. Earlier this week I ordered something and was told that someone would be there between 5PM and 7PM. So I unlocked the door at 4PM. He arrived at 6PM. I asked him to lock it on his way out. He did.
Only person who comes by is the landlord @once a month with groceries and my mail.
No hallways. It's a fourplex and each front door opens to the outside.