this is also why it's a 10 minute block time target btw. the minimum propagation time on the internet for a block is about 12 seconds, but reorgs can happen and it can take time for those to become high confidence. a lot of altcoins use even down to 15 seconds (ethereum's PoW consensus was this fast) but this doesn't allow for avoiding a lot of chain splits. 10 minutes helps ensure bitcoin's miners are always targeting the main chain and avoiding growing side chains.