memes

It can vary depending on how the store sets the machines up. I'm on the wrong continent to use Walmart ones, but there's definitely variation in how paranoid and slow they are set here.

I feel it's one of those cases where if you're familiar with them and can think like the person who designed/programmed them, it can work pretty well. If you get confused by unfamiliar card terminals or a phone doing an update, you're in trouble.

E.g. it uses an expected weight and tolerance for products going into the scales. If this is produce you've just weighed, it's going to be pretty precise. Same goes for something really light like a toothbrush; a 50% margin on tens of grams is still not much. If it's a prepacked bag of oranges, then the weight could be way off (add a whole orange over the expected weight) so it won't alarm on e.g. you putting a reusable shopping bag on the scale with the oranges. This lets you skip the annoying use-your-own-bag process.

Knowing and remembering which is the next button to hit helps a lot.

I find they're fine for <5 items especially if the store is busy, but for a full trolley, you're better off with a lane just for staging reasons.