[dsr_]

It's entirely possible that he had nothing else to do but read that month. If there was no album currently in production and no tour going on -- both of those things seem plausible for that month -- then it was all available time.

The Great Gatsby is short. Candide is shorter. The Picture of Dorian Gray is fairly short. Each of them might have been read in a day or less. War and Peace is famously long, but at a normal reading pace of 200 words per minute it will only take 40-45 hours -- say, 10 days.

[Thrymr]

"Catch 22" was also presumably read for work, he played Nately in the film version that was in production in 1969: https://www.imdb.com/title/tt0065528/

[Lio]

Even if he was on tour, it’s conceivable that he had a lot of time in transit to kill.

I’m great at reading in cars but trains and planes are ok for me.