Natives rebuild every time I add a dependency, using either npm or yarn

Adding any package, using either npm or yarn triggers a vert time expensive rebuild of all the native binaries for opencv.

Ubuntu 18.04
Node v10.15.0
npm v6.4.1
yarn v1.12.3

I have no rebuild commands in my package.json etc...

I have just set the set OPENCV4NODEJS_DISABLE_AUTOBUILD=1 while waiting for it to compile once again and am yet to test it.

Help certainly appreciated! Thankyou
Any ideas?