I regret that the following might be relevant to you attempts at maintaining standards.
We stayed two nights, and were highly surprised that, on the first morning, the cleaning service knocked on our door at 8.30 am with what sounded like a key, uttering "room cleaning" then kept repeat that procedure throughout the corridor, eventually returning to our door, upon which we opened to send her away (sorry, I was aggressive then, as I had hoped to sleep longer--it was New Years Day!), then she repeated the same _once more_, and on what must have been the fourth or fifth time--by which we had stopped responding and had crawled under our pillows--opened the room, stepped in, must have seen us lying in bed, and left, only to return once more shortly thereafter.
I had after the second incident called the front desk, asking them to stop her--but to no avail, it seemed. The sixth time(!), upon which I literally begged her to leave us in peace, she was kind enough to tell me to put out the do not disturb sign.
That, luckily, worked!
We think a solution would included (i) informing guests--who might be used to room service knocking on their door _after they have been to breakfast_but not before --, upon check-in, to put out that sign; (ii) asking cleaning staff to use something that produces a low noise signature to make themselves known (we kept hearing her as she made her way across the corridor to other rooms).
Relatedly, the doors fell close so loudly, we could tell something is going on in the room opposite and to each side.
Finally, since we left at 4 am for the airport the second day, we had asked for a breakfast box, which we thought was a great service. Now whatever was in there had such a bad smell (of fish, my wife says) about it that we chose to dump the food at the airport right away.
A coffee to go, juice, some fruit, and a piece of cake or sandwich would be the far better option, we think.
Otherwise, no joke, we did enjoy our stay! Thank you.