Interested in Language
I'm a bit puzzled as to what is the exact sentiment behind the construction such as this:
I didn't find (that) many mistakes at all.
If we break it down:
(1.) that many
(2.) at all
I didn't find that many mistakes -- There weren't many mistakes, but I still found some.
I didn't find mistakes at all -- There were NO mistakes.
But (1.) + (2.) = ?
It's softens the criticism. It makes "that many" feel even less.
Don't worry, although I did find mistakes, they were very few in number. I didn't find that many at all. (Either you or I thought it would be worse than it was.)
Don't try to break it into its parts. Just go with "not that many at all" to be "a small number, and possibly smaller than expected."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.