When playing live, songs are usually much faster than the album version, particularly for rock and metal. When you listen back to early demo versions of those same songs, they’re usually a fair bit faster than the final recording, too. So at some point along the way, someone decides “ok, we’re setting the tempo at X BPM when we record this for real”, which is - apparently - not the tempo that came naturally to the musicians originally, or afterwards when touring the album.
How do they decide? Is there a rule of thumb producers are working with when it comes to the speed of a recording?
Cheers!
I honestly can’t say with 100% certainty but I can speak to my experience with playing in an ensemble. For small sets, think a duet like violin and piano, usually there is an agreed upon “lead” and the other player(s) match them. In larger ensembles, band or orchestra, the conductor is god so we should be following them for tempo and queues. That being said, we listen to each other for certain queues and phrases to know when to join in. Generally we match whatever percussion or bass is doing, because that’s usually where time is kept.