For intermediate and advanced players, using the area of focus concept helps you work MORE on improv or comping. This is not meant to be used by beginners.
The idea is simple, when building a basic training program for yourself, if you choose to have either improvisation or comping as your area of focus simply:
Here's an example:
Your basic training program consists of Warmup 10%, Repertoire 50%, Scales and Arpeggios 20%, Chords and Comping 20%. That's your basic template from previous lessons.
Now, should you considering spending MORE time honing your comping chops (for instance) you would increase your comping time to 30%. Makes sense?
Now, since you have more time dedicated to chords and comping, you should also align this time with your current repertoire. How? Simply by applying whatever you're working in comping to the chord progression of the songs in your program.
Personally, I would even cut back little bit on the Repertoire time, to make it 40% instead of 50%. Because you'll be working on repertoire through comping stuff anyways. Remember, the goal is to make the comping stuff the area of focus.
Let's see the new program, with the area of focus chosen to be "comping":
(We're left with 30% of our time, so split it in two)
Chords: exercises, learning new chords, etc. 10%
Chords: applying in comping on repertoire 20%
See, we carved out a chunk of time to spend more energy on chords.
It DOES make a difference how you "align" yourself with this area of focus. The key here is experimenting, and finding what works for you. For instance, you may elect to even cut back on the scales/arpeggios to make more room for comping.