New to the crypto space, please correct me if I misunderstood the meaning of block time.
When a cardano node submits a transaction, it goes to a local mempool and submitted on the blockchain for verification. Let's assume this part is instantaneous from the wallet node.
The official docs state that blocks are produced every 20 seconds. In other words, even if the validator nodes receive the transaction immediately, they will wait upto another 20 seconds, and then create a new block to broadcast.
This implies even a low assurance for block will take atleast 20 seconds. In my experience with cardano wallets (before the dexes were launched), it rarely took more than 10 seconds to get a high assurance for transaction.
I also read on the forums that 20 seconds block time is configurable, and can't be enforced on a node. So are we relying on SPOs to use a low block creation time interval to solve real time transactions in the long run?