Ugh. The best time, IMO, to get a Redcard is when the guest is watching their total go ever higher and higher and they are hearing the words "5% off". But until they get to the realization on screen how much they will be spending, unless someone has talked to the about it when they are staring at the shelf price, or they already have it in mind from prior knowledge, it's just another pain.
It's like when the new Sam's Club was going up here, Walmart had a billion people in the store pushing people to sign up for memberships. I felt bad for the employees, but I really did not need to be asked 5 times in one trip for something I did not want, and I hated having to go out of my way when I saw the associate coming so I could avoid having that conversation yet again.
Note: if Spot would carry my cat food and cat litter, I wouldn't need to go to the big blue box nearly as often.