Does it only take hours for a US check to clear any US Bank?

I read recently that US banks had changed their internal systems and now it only takes hours for a check drawn on a US bank to clear any other US bank even if it is in another state. Is this true?Does it only take hours for a US check to clear any US Bank?
I'm sure a check can be cleared within hours or at least in the same day with today's technology. The whole 3-5 business days to clear a check is just a way for the bank to hold onto your money for those extra days and use it to invest in other products that will earn them $$$. So they're using your money to make themselves money.Does it only take hours for a US check to clear any US Bank?
Its only as fast as the mail can deliver it.
My bank says it can still take up to 3 days to clear.