The Bitcoin network does not look at how long a transaction took. It doesn’t make the decisions about when transactions should take place. There is no set answer. That will depend on many technical factors. The size of the transaction has nothing to do with how long it takes, and the value of the transaction does not have anything to do with how long it takes either.
At a high level, a transaction is confirmed when it is permanently included in the Bitcoin blockchain. The important conclusion, however, is that there is no absolute notion of permanent inclusion and that the community is merely using a reasonably safe policy of considering confirmed transactions when they are included with very high probability. The time it takes for this to happen is highly variable. Sometimes a confirmation can take ten minutes and sometimes more than two hours, but on average, it takes about an hour.
You’ve probably heard of the Lightning Network and how it would be beneficial to your businesses. Maybe you want to give it a try as a merchant to see if it will work for you. Or perhaps you want to give it a shot and find out for yourself if it really will be a great way to use your money.
Bitcoin’s almost immediate physical settlement opens up vast design space for developers to add cheaper and more convenient payment networks with deferred settlement. Lightning Network and other second-layer solutions enable inexpensive, near-instant transfers that install periodically in the base layer. Not all transactions deserve final settlement as quickly as possible, as do VISA, ACH and other existing systems. For a very low-value transaction, for example, it would be better to use a higher level on the blockchain, which will take longer to confirm, but which will cost less.
How many transactions per second can a payment network such as the Lightning Network handle on Bitcoin? It depends on how large the system gets. We don’t know because we don’t know how much money will be moved into this network.