So from my personal BTC explorer, i realized that sometimes a blockchain isn't really 10 minutes or anything close. I often experienced blockchains in-betweens taking way longer than 10 minutes say 30 minutes or 25 minutes.
That has been well explained above, and maybe you have not be noticing much about the time the transactions you are broadcasting take before they are confirmed, or maybe you can try to make use of the explorers or sites like
https://mempool.space to check when each block are mined for long time to see the difference in time transactions re confirmed.
Transaction can take just less than 2 minutes before it is confirmed, it can be confirmed any minutes the transaction is broadcastimed, it can even take 30 minutes. That is why mining difficulty is adjusted every 2016 blocks. It is like that because if more miners join the network, the mining hashrate increases, and this will lead to transactions cmgetting confirmed more below 10 minutes. But if miners stop their miners from working and are not mining, the hashrate will reduce and transactions will getting confirmed more above 10 minutes.
Which mean that transaction confirmation can take less than 10 minutes or more than 10 minutes, but will be almost 19 minutes on average if the average of the total transaction is calculated.