It is the default. So it ends up with un-optimized structure sometimes. Because the top package is locked and does not meet the version new package required.

It is the default. So it ends up with un-optimized structure sometimes. Because the top package is locked and does not meet the version new package required. In order to satisfy the constraint. Npm will install second copy of the package in nested directory. And npm also have a `dedup` command for you to `screw it, change the version in lock and merge them if possible`.