Older versions of node especially had problems resolving mutual secondary dependencies efficiently, though all versions struggle to an extent. Sometimes you hav

Older versions of node especially had problems resolving mutual secondary dependencies efficiently, though all versions struggle to an extent. Sometimes you have to declare a dependency at the top level in order to force the most common one to be installed at the root, so the less common one gets installed in all of the places it is needed rather than sharing the single one at the root. The likelihood you ever get back to zero copies of that module are fairly low, unless it has become persona non grata for some reason (leftpad). So it's easy to forget to back out the disambiguation entry at the top level. Especially if git blame doesn't make it dead apparent (see also people manually adding entries in non-alphabetic order so that the next 'npm install --save' rearranges five lines).