Let's be honest, making a trip to Costco isn't "planned." It's basically either rush over on lunch break (or anytime during work hours for remote workers), or spur of the moment.
I've always found it suspect that no appointments are available for 5+ days in the future, for the 3 closest to my home.
Then, I check the one near work, and they have appointments today. Problem is I have to pay the bridge toll to get there. I will. I can hit the car wash while across the bridge (monthly).
But my point is, I think it's suspect that 5 Costcos have zero appts well into the future, then 1 has them as soon as this afternoon, and every single day into the future. As if most stores don't use appts, or, on purpose, they book them all so none show up.
I have glanced over at tire shops and have seen zero to one car in the bays, on a weekend. The only one that has no availability as in not ever, is the one in Delaware. People from PA/NJ/DE/MD/VA/DC are all getting tires installed no sales tax.
Think about it, what would you do if you got a flat, wait 7 days and make an appt.?
The disclaimer is walk ins are available. For such a huge organization, they need to improve on scheduling. I once made an appt for right before closing, and was called and told to come in sooner hahahahahahahaha