I seldom use room service when I travel. So when I actually put away the "do not disturb", it's because I actually need something. Either I've totally used up all of the little towels (it's amazing how filthy I get with a combination of dirt and sunscreen) in the shower, or I'm running out of something critical like toilet paper.
So after a long day in the field, I was somewhat irritated to find that housekeeping had indeed gone through as requested, but the only apparent impact to the room was that they had short-sheeted all the blankets. This was more annoying because of what happens when I come back from the field:
1. Close door behind me.
2. Draw deadbolt/latch.
3. Immediately strip off all clothing and drop it in the vicinity of a closet.
4. Jump in shower.
Checking whether or not I got the toilet paper I needed is way down on the priority list, and then it's a bit late to go running down to the lobby.