Another little side factoid kind of thing, a lot of people have an image in their minds of the complete band and singers in one studio all at the time, creating the music. In reality, that was a rarer occurrence as it's not always easy to schedule everyone for sessions. Thus much production, as was mentioned further down the wiki article describes how some tracks were laid in spring of the year and final work was done november of a year.
It's not unusual at all that many artists were never in the same studio together throughout music production history. It was even tough for Motown to do this consistently. Movie filming is the same way. It's in the editing that the magic mostly happens.
An old family friend and my older brothers old band mate is now one of the most sought after record producers on the east coast. Very humbling that I hung around in the jam basement with those guys.