Comment by IshKebab

In most cases it's definitely better for it to be fast. For example I sold a buggy face to face today and they paid me by bank transfer, and the reason we could do that was that I had a high confidence it would turn up quickly and they weren't trying to scam me. It actually took around 1 second which is really quite fast.

You don't need slow transfers to get an opportunity to satisfy automatic payments. I don't know how it works but in the UK direct debits (an automatic "take money from my account for bills" system) gives the bank a couple of days notice so my banking app warns me if I don't have enough money. Bank transfers are still instant.