Lots of people keep it on during the day! Especially if we're not frequently in and out. Example: I work most of the day in my office at the back of the house and wouldn't hear someone breaking down the front door, let alone climbing through a window :/ I have office machines, TV or radio on alwayys and I'd ESPECIALLY hate to be caught unawares while sitting on the pot. Some bathrooms have fans (lol) that turn on when you turn on the light and I would never hear anything when I'm in there.
Many crimes are crimes of opportunity and if the house looks like no one's home, they'll take a chance - smash, grab and go. It's always on so I have to turn it off to open the door and get deliveries, but I don't mind that a bit. Nothing's foolproof when criminals want to break in, but I feel safer in my mind at least.
I'd be absolutely paranoid if I lived/worked in a house of 10,000 sf! That's incredibly huge and especially with old homes built so solidly, it could be doubtful you'd hear what's going on in another part of the house depending on where you are vs a break-in.
I do understand people feeling a little more secure when other people are in the house, though, and maybe not arming the system, but not me. It happens once, you don't take it for granted again.