On our trip in August, we made three last minute dinner PS. The first was on our arrival day. I had planned on eating in Orlando, but dear hubby didn't want to hop back in the van. So I picked up the phone and we had a PS for Kona Cafe, thirty minutes later. Just hopped on the monorail (we were at the Contemporary.). Two nights later, he didn't want counter service, so I again picked up the phone, and we got a PS for Whispering Canyon Cafe for 45 minutes later. The third one, we had moved over to Beach Club Villas, we had again planned on counter service. But everyone in our party really wanted a sit down meal, so I picked up the phone and we got a PS for 40 minutes later at Restaurant Marrakesh in Morocco.
As long as you are flexible in your restaurant choices and times, I think you will be fine.