I have always done that including the very first trip in 1983. I made the mistake of staying onsite only once and it was the most expensive trip to WDW I ever took. I hated every minute of it. We and I always ate breakfast before going to the parks in one of the million places on 192. Have a quick service lunch and a few snacks in the park and around 4:30pm we'd leave and have a slight rest at the hotel, change clothes if needed. Go out again to one of the million restaurants on 192 and head back to either the original park we went to in the morning or since I always bought parkhoppers, go to a different one until closing. None of us were much into souvenirs especially at those prices and if we wanted a Disney trip souvenir we'd go to the gift shops (still on 192) and buy them. I can't tell you how many T's I bought for around $7 each instead of the $25 ones onsite. Here's a little secret. The T's were with an approved Disney label, quite current and lasted longer than anyone I ever bought onsite. There were ways until they went crazy with prices to just get into the parks which have caused the whole thing to be hard to afford, especially with a family.