Mine is in steady decline... and I live in New Orleans, a city of wonderful food. I've just discovered that any wait of over a half hour or so (at a place that doesn't accept reservations) is almost never worth it to me.
I try to patronize places for lunch instead, if I love the food, but standing in line just almost never seems justified. I'll get all kinds of "exceptions" thrown at me, I know, and I'd be more willing to do that - or wait even with a reservation - for a truly stellar restaurant experience with a cuisine I can't get here... but I'm just less patient and a better home cook than I used to be, I guess.
What's your limit?