Sargent Pepper was recorded on a 4 track machine, an amazing feat. They would record with all 4 tracks and then use a technique called bouncing where they would move 3 tracks over to one. That would free up 3 tracks and they would repeat the process over adding layers of instruments which would add depth and space along with primitive tape looping adding delay and echo.Everything was painstakingly edited with razor blades and taped back together.It took a little over 5 months and the music world writers at the time we’re saying the Beatles had dried up and ran out of ideas. Hahahahaha!
You reminded me of my first multi-tracking experience:
Two cassette decks. One microphone. Record on one machine, bounce both tracks onto the L input of machine two, while recording to the R input live. Swap cables, bounce both tracks from machine two onto the L input of machine one, while recording to the R input live.
Ugh. By the time I’d recorded all the parts, the first tracks were degraded horribly. The first Tascam 4 track Syncassette machine I owned was a revelation! Then I could do THREE tracks before bouncing down to mono, and had three more tracks to work with. Never had to use more than that! But the mixdown on that bounce operation had to be right.