It sounds to me like even the great Led Zeppelin (and I don't mean that sarcastically -- they're one of my favorite bands) was having some problems toward the end there.
I know that the whole band doesn't have to be there while each individual member records their parts, but usually there's a certain amount of "hanging around the studio" while it's going on, just because they're a band and enjoy hanging out with each other, and also because there can still be some give-and-take and suggestions about how things could be played, even at that stage.
When the various members of the band don't even bother to show up on days when they're not recording something, to me that's not a good sign. It's kinda like hanging around your workplace before or after your shift, or even on a day off, just because you like the place and like hanging out with the people there, even if you're not working. Nowadays, I wouldn't even think of going in to the office if I didn't have to, if there wasn't something I had to do there. It's just my job. But I like making music. I like hanging with the guys in my band, and if we were cutting an album, I'd hang out and enjoy the process, even if I'm just watching and listening to the other guys lay tracks. When your band becomes "just a job" and you don't bother hanging around when you're not "working", something has been lost.