I think Audio Boost is a track setting so you have to use it on the whole track.
Edit-Gain Change can be used for smaller sections.

When amplifying a whole track you are often boosting noise in a lot of places, so doing it in sections is often more inviting here.
When boosting it all I end up wanting to cut or lower the noise areas (which is about the same amount of editing work anyway).
Just came to mind with your question, maybe its just me and how I work. Now if you're using it temporarily in a session, track boost can be real handy.

I do not work here, but the benefits are still awesome
Make your sound your own!