Exactly. We have done this the past 4 trips and never had an issue. This summer there will be 21 of us on the DxDDP, so with the number of us ordering appetizers and desserts, I have no doubt our 7:15 reservation will last 2 hours.
We typically arrive about 15 minutes early and ask for a table outside if it is possible. We also let them know we are willing to wait past the reservation time if needed. We are always polite and let them know we understand if it is not possible, it's just a request. If we don't get the patio seating, we know there is a reserved area where we can watch Illuminations.