If these are the ones for a company that uses another app to record them, I have found that they can be a little hit or miss, but the comments above are pretty accurate.
A busy gas station can take a while if you have to wait for customers to leave, because they want you to take a picture of the register pricing in the app, but also not disrupt the operations of the store. Hopefully you don't get stuck behind 10 people buying lotto tix.
Some of the places can be sorta grimy - I did a few smoke shops and they had the merchandise on the floor instead of on a shelf, it was dusty and cobwebby - gross.
I also did some of these at the gas stations affiliated with a blue big box store - the cashiers were scared to do price checks on the register, it was kind of bizarre but I do think getting pricing done by outside vendors is normal so I'm not sure why they were reluctant to do it.
I wouldn't do these for less than 17.