Always one game.
In my ultra keen days. (I refer to them as my chess and cornflakes days when
I would eat my breakfast whist looking at games of chess or positions and
that would be the theme for the whole day.)
I would put games through a mind mangle squeezing out everything and
often being left with a whole batch of unanswered questions that needed
Great days. Often I would analyse myself into a deep whole and have to start
all over again.
In them days no computers so you had the added bonus of perhaps finding a
quicker win or an outright blunder in the notes.
It was not all that uncommon to find a 'hole'. It's where the saying:
"If it's long [analysis] then it's wrong." came from.
If you found something you either kept it to yourself if it was in an opening
book or fired off a letter to CHESS or BCM.
Mr Thomas mentioned in Fischer's 60 was such a letter where he found a
move that Fischer had missed that would have forced immediate resignation.
The whole history behind this note and some more Fischer 'Mysteries' can be found here.
I recall Tony Miles spotting a blunder in one of Levy's books on the Dragon,
using it and winning a game.
Also in the first book on the Benko there was a glaring hole. (see below)
These days a computer has run over everything and you will not find any