so in the first few rounds. they start with empty block.. and start adding more transactions per round.
(much more efficient this way to start with 0tx and add a few every extranonce round)
I'm not sure that's correct.
If they added a few transactions every time they incremented the extraNonce, then we would expect not just to see the occasional empty block, but to also see a not insignificant number of blocks which could have been 100% full but were only 5%, 10%, 15%, 20%, etc., full.
firstly. i was dismissing the fud that 'pools like viabtc do not own a full node and only have a litewallet to their name'(SPV).. as that FUD is completely factually incorrect.. the myth that pools only own litewallets(SPV) was done so to create some propagandist FUD that pools are dirty, nasty, dangerous to the network (a rhetoric being passed around for the last 7years)
viabtc do have a full node.
what you need to realise is about the timing.
it was much more observable in the past due to slower asics and slower propagation and lack of things like compact blocks and such.. meaning the timing between rounds was more noticeable
its only no longer now the case seeing how pools function behind the scenes because asics have got faster and propagating blocks and transactions has got faster.
once a pool purges confirmed transactions from its mempool. adding new transactions is a millisecond event. it was never a case of after 2.5mins =35% after 5mins=50%
which you are presuming...
years ago. pools would add their own few transactions they knew were not in the previous block because because they knew when they received the transactions and validated them to add them to mempool.
so would add a few transactions before the confirm purge.
then in later rounds added more transactions after the purge of confirmed transactions found in the recently solved block(usually a full block of them)
as i already said. it was never a scientific thing of oh 25% full that must mean 2.5minutes. 50%full must mean 5minutes..
it was more of a 0 full = few seconds. under 100% = few seconds to minute.. full= minute+
lets take an example
viabtc
https://www.blockchain.com/btc/block/734379- not full
precedeing this was
https://www.blockchain.com/btc/block/734378 - not full
https://www.blockchain.com/btc/block/734377 - 'full'
as you can see XX78 and xx79 are both solved quickly after, but not empty nor full