I had a brief rabbit hole about chess at the beginning of this year and found out a few things pros do to prepare against their opponents. I was trying to remember one specific periodical, but I found it: Chess Informant. 320 page paperback (and/or CD! - I see they also have a downloadable version for less[2]) quarterly periodical full of games since the last one. Looks like they're up to volume 161.[1] I suppose pros also get specific games they want sooner than that, especially now with everything being streamed, but anyway. There's a lot more going on in chess that is just as important as the time spent actually playing in the tournament.
Honestly, your anecdote makes me respect him even more.
Few people go to those lengths to prepare.