TIL a dry erase board on the job trailer door cut my sub calls in half

Had a 3 week stretch on a small tenant buildout in Fort Wayne where my phone would not stop ringing from subs asking the same stuff over and over. I was spending about 2 hours a day just answering "when do I get the room" type calls. One morning I zip tied a cheap 2 by 3 dry erase board to the inside of the trailer door and wrote the daily schedule plus a note about who had the space and when. First week my calls dropped from maybe 15 a day to 6 or 7. Turns out half the guys were calling because they did not want to bug me, not because they had a real problem. The board gave them an answer without the phone tag. Anyone else tried something this low tech to cut down interruptions, or does it fall apart once the crews get bigger?