With clip gaining you change the audio file itself. Directly. I prefer to do this as it means I have much greater control, and faster too, over what happens down the line in terms of effects. It works equally well even if you send audio outside for outboard processing.
I break up the audio where needed and I level-match these clips before sending the audio down the line. Any small fade-ins and fade-outs to each clip I also do here. Perfect for manual de-essing as well.
This way the compressors work more gentle and with less side-effects.
I duplicate tracks with send effects like reverb and delays at different settings as well. Again, much better than automation which requires constant tweaking.
Automation is to me a dead end and very counter-intuitive in comparison to clip gaining. Clip gaining wins on KO in this house.

Find my music here:
https://espenkraft.bandcamp.com/album...