Ionic 3.3.0 when is it necessary to run npm install

Probably a dumb question?

The latest update for 3.3.0 does not mention deleting the “node_modules” folder and running “npm install”

Is this always necessary, or optional in this case?

Whether you need to delete node_modules or not is a bit of opaque npm voodoo, but any time you modify package.json, at a minimum you must run npm install afterwards.