I recorded this laid back song using the Crown CM-311A, and I seriously doubt that Garth is using anything differently than I am, though he has a full crew and in my case, it's just me at the controls.
https://app.box.com/s/mhs7lgmkzxwnmik557ol2ere7wbuyzqu I don't know about extreme compression, probably because I never used it. However, I don't scream into the mic and pull it away (proximity effect) because I cannot hit the high notes, which I've seen on so many occasions during the past 60 years on stage. One of the very first things I learned from my vocal instructor at Harford Community College, who was an accomplished jazz singer, was vocal/voice control. She was a master of this technique and regarded as among the top jazz singers in the Baltimore/Washington metro area.
Now, I will be the first to admit that I have a relatively soft, smooth voice, and for me, vocal/voice control was very easy. Additionally, I had some training as a newscaster, which also made utilizing vocal/voice control very easy to master. AS a newscaster, you needed to place a lot of emphasis on certain words and phrases in order to make the news story more exciting and interesting - just the same as you would do with many songs. This led to bigger and better things for me when I managed to land several jobs doing voice overs for automotive commercials during the ensuing years. No proximity effects here, just vocal/voice control to get the point across to the audience.
Some folks are comfortable with a headset mic, and some are not. Some can make it work and some cannot. Use whatever works best for you.
All the best,
Gary