I think going on your last day and it being a saturday is just fine.
I read another post on another thread that made a lot of sense.
Hollywood Studios is busy almost every single day, it's the smallest park and doesn't field crowds as well or have as big of a capacity.
Whereas, the other three parks are busier on weekends compared to weekdays.
so keeping DHS on saturday actually makes a lot of sense because if you were to change it to say wednesday, you would still have a busy DHS day on wednesday too
and vise versa the park that you would switch from wednesday to saturday would go from being relatively lower to now pretty crowded.
we went our last park day and the only reason why i maybe WOULDN'T recommend it was because of Rise. Luckily, we got a BG just fine. But the others' in our party had asked if we could switch days when we were in the planning process so that if we went to DHS first, didn't get Rise that we could try again at a later date in our trip.
(We also had read whether it was true or not that if you make a big enough stink about not getting Rise and other parks have availability that they would at least give you an option to switch reservations and go to another park that day instead of having a wasted day).