He does say "passage" to refer to a small part of a composition, not the whole thing. Your thinking is spot on though -- the length of the segment needs to be considered.
You need to adjust the segment length to reflect your current success/failure. Either that, or you need to slow down. I'm viewing this from a musician's perspective, but those are the two basic tools in my practice toolbox:
1) slow down until comfortable
2) isolate the thing that is giving you the actual trouble, and fix that before attempting the bigger challenge
The thing to avoid is practicing mistakes. These two basic principles attempt to minimize that.
1) slow down until comfortable 2) isolate the thing that is giving you the actual trouble, and fix that before attempting the bigger challenge
The thing to avoid is practicing mistakes. These two basic principles attempt to minimize that.