I tried to get a reservation at Le Cellier at EPCOT, but when I called around 7am exactly 180 days out for my ADR. They said there was nothing available. I was kind of shock to hear that there was no reservation available on that day. Than when I do the next day at EPCOT and got up earlier around 5am, once again there was nothing available. I don't know what I have to do to get a reservation at Le Cellier.
You are right that people do cancel at the last second and some walk up person can get in the restaurant without getting a reservation. I would like to do more dinner plans during my trip at the WDW resort, but I would prefer to eat more off property and save more money during my trip so I can use to buy merchandise. I definitely will write it down on my TR about each different restaurant.
When I was doing my research for our trip, I found out that if you are staying on-site, you can make ALL your reservations 180 days out from your first day...so you could book Le Cellier 185 days out if it was for your 5th day at the parks. So that is how they can be booked already. I read that Le Cellier and Cinderella's Royal Table are the hardest to get.
We went in Sept during free dining, otherwise we NEVER would have eaten at all those expensive places, so I completely understand.
We had early, early breakfasts at Tusker House, Crystal Palace, and I can't remember right now the third. We also had lunch/dinner at Tutto Italia and Tony's Town Square. We ended up canceling all of our other ADRs - it was just way too much food - we are not that big of eaters, lol. But we thought all the food was excellent and the CMs were great at the character breakfasts about making sure all the characters went to each table. At Tusker House, at the table next to us, their camera battery died just as the characters were coming to our section. The mom ran out somewhere and got new batteries, but meanwhile, two of the characters had gone by and to another section of the restaurant. But when a CM heard the story, she had those characters come back so the family could get pictures.