but not impossible. Usually, you see trip cancellations around the 45 day mark; because, it's when final payment is due. That's the best time to snag a last minute reservation for a meal. After that point it's harder.
You can try a walk up; you never know; unless, you try. There can be a few people who decide to sleep in and skip the meal that day. Maybe, they were up too late the night before or maybe someone got sick and so forth. It's a gamble, but if you are there anyway; try it.
Right now, if you want the place more than anything take an early lunch. At least you'll be able to eat there. If a breakfast reservation comes along as you look each day, then you can cancel your lunch time one and get the breakfast time.
I have been able to snag a few tough reservations last minute, but you really have to be deligent about looking and looking. I was trying like 4 times a day and did it for over a wekk , but I got one. Good luck.