Does it take THAT long to add a few Transactions to a Block? Are a few seconds not enough for at least one of them to be included?
The mining pool still has to validate the entire previous block before adding even a single transaction to a new candidate block.
Let's say I validate the first 10% of the previous block. I then decide to add Transaction X to my new candidate block. How do I know Transaction X hasn't already been mined in the remaining 90% of the previous block? I don't. Is it worth risking the 6.25 BTC block reward for the few thousand extra sats I would gain from mining Transaction X, versus invalidating my entire block because Transaction X has already been mined?
Before adding a single transaction to my new candidate block I need to verify the entire previous block. It only takes a few seconds (or even less), but on occasion this is all that is needed to successfully mine an empty block.
not quite
most pools already validated most transactions to even get into the mempool. to already get into a block. so they dont need to do any validation on their own block.. its actually 2 other things
a. the exclusion of spent UTXO inputs of the UTXOSET and the inclusion of outputs into the UTXOSET
b. its also then ordering the mempool in feerate order and chosing candidate transactions which add upto the block limit of a candidate block
whats also happening is the asics dont sit idle waiting for a full block header to hash. they have been given a empty block blockheader which gives them a nonce+extra nonce range to work on before asking for extra work via a update of a blockheader. its those few seconds of mining a nonce+extra nonce range that takes longer then the pool making a full block template header to then send to asics
