I don't try to compete with Costco's $500,000 printers or their $3 price for great 12X18" Lustre prints, so I don't try to. I can upload files at 1AM & pick up the prints at 10AM, which is fast enough to make me happy, & I don't have to think about maintenance.
The people at my Costco are excellent, & have been for 7 years. In my case, they're faster, cheaper, & every bit as good as the pro lab that I used for decades. OTOH, there have been a (very) few mentioned in the forum that don't make the grade.
As for my local pro lab that I used for 30 years & paid for most of their new wing, they want two days normal processing, 10 times the price, & won't provide a printer profile. I'll only use them again when they can provide something that Costco can't.
Each store has their own profile, & they're updated about once a year. Mine does it in the Fall. OTOH, I forgot the profile once & the 2nd profiled print came looking the same! Just lucky that my color space was the same as their profile, I guess. I asked them & they said that they've noticed that there wasn't much difference, either.
If you use Image> Mode / Convert to profile, uncheck the ICC profile box at the bottom when you File> "Save As".
DO NOT use the Fast Upload option, unless you like having your file size reduced by 95%
Don't use the mail option, as Costco doesn't print those.
Turn Autocorrect off. It's just before clicking on "Place Order" at the end.
Does costco adjust photos brighness when printing?