I once was confused about Offset mode, now I use it all of the time. Yes I use it when I have automation on a track and I want to adjust the over all level.
But how I find it handy is I use it to set my general over all mix, this way when I am in automation mode, all of my faders and pot are all at zero now when I do add automation I have a more precise control when dropping or raising parameters (especially my faders) notice how on a fader, the lower it is the db's are closer together.
Meaning when a fader is set to lets say -18 and I want to raise or lower my signal by a couple of dbs I have a to make a very small adjustment, but if my automation faderes are near zero, I have better control because of the difference in "space" between db adjustments.
Yes when first started this method I might get a little confused, but I would remember Offset mode, now that I use it all of the time, it is like second nature to mix in offset and make any automation while in automation mode.
This might come from my live mixing habits as I like to have all of my faders right at or near zero, because I can make finer level adjustments when the fader are at or near zero than I can when a fader is set to -18.
I hope this makes sense, and helps someone out as to why we would use Offset mode. I know I miss it when working in other DAWs
Tom