We leave $5-$10/day during our stay (usually it comes down to what cash we happen to have on hand), not only to acknowledge the hard work of the Mousekeeper, but to hopefully get our room serviced every day at a reasonable time!

It's always so massively disappointing to be out from before rope drop to, say, 4pm, only to return to a room that hasn't been serviced yet. I'm not sure this strategy actually affects when our room is serviced, but it sure SEEMS to. We write a note with the cash and haven't yet not had it scooped up. We also do $20-$25 on our check-out day.
I'm still new-ish here so not to get off topic, but while I agree that tipping culture generally is out of control, and it's not the customer's responsibility to supplement underpaid workers, and that plenty of people do hard work and aren't tipped (etc., etc.), I can tell you that I worked for 2 eye-opening summers as a housekeeper in a busy national park lodge, and it is backbreaking and often absolutely disgusting work. Back then, I'd say only 10-15% of guests left a tip (we weren't allowed to take any cash from guests mid-stay, even if there was a note or an envelope, but we could keep obvious tips left in the room after they checked out). Before that job, it never occurred to me to tip housekeepers, but I have ever since.
So: From a former maid, please know that tips were always SO appreciated, even if it was just a dollar or two. And while you may be neat, the next 5 rooms over might each look like a frat house and a crime scene had a baby!