Turning off shrinking makes little sense to me. If tests are passing there's nothing to shrink. If you are bombarded with so many failures you can't afford to shrink them then more testing is pointless.
The author’s point is that shrinking can take a very long time, and that’s what you should consider turning it off. In my experience this is also true.
They’re saying that sometimes it’s better to just see the error in full and try and figure it out.
That is not my experience (doing this sort of testing on compilers). In my experience, the shrinking is usually very fast. When it takes a non-negligible amount of time, debugging the failure would have been hopeless on the non-shrunk input.
What takes the time in my case was simply getting a failure to occur at all. It might take days on a mature compiler before a failure occurs, if then. This would be millions of attempts.
They’re saying that sometimes it’s better to just see the error in full and try and figure it out.