How busy are counter-service places in December?

[javaj]

Our trip dates are 12/15 to 12/25, definitely planning to make lots of PSs (already have our LTT MVMCP 12/16 PS). But how busy are couner service restaurants during that time? Obviously we won't be able to eat at a sit-down for every meal, so I'm just wondering if there are any good things to know to avoid lines/waits for food at the counter service places. I'm guessing it'll be pretty packed during typical lunch/dinner hours just like always, but will it be bad all day long?

Thanks!