Anyone have the same daycare and overnight rate?

I'm trying to figure out my rates. I tried raising them from $20 to $25 for overnights, but I got far fewer stays (even though this was on lower than other sitters in the area). I also added daycare as an option, but our overnight rate is back down to $20 and I feel like $15 is too low for daycare.

What I've been doing is charging the same rate ($20 for daycare or overnight) and offering a $10 discount for 3+ days of daycare per week (3 days in a week = $50). I justify this in my head because daycare requires me to be available twice in a day at specific times, so I have to plan my entire day around those times (errands, dog hikes, etc).

Is this approach reasonable? Does anyone else find daycare just as challenging as overnights (just for different reasons)?