The point of such an exercise is not some sort of magical expertise, but simply reducing the complexity you are dealing with so you can concentrate on other matters. It's the film selection equivalent of minimalism. And it's very definitely not for everyone.
I do recommend everyone try it, if only so you can evaluate other things. If you want to dabble in developers, test everything with the same film. If you want to dabble in films, test everything with the same developer. Even though some combinations may not be optimal, it will for the most part give you a level playing field.
I fell into this by accident myself. When I started shooting B&W seriously, APX400 was dirt cheap at my local shop, and so was Rodinal. Rodinal was easy to work with and the cheapest option. So I shot a lot of APX-400 and developed it all in Rodinal. When APX400 became unobtanium, I moved to Tri-X and shot a lot of that, still using Rodinal. Then I tripped over 4 100' rolls of HP5+ in water-damaged packaging for next to nothing, I bought them and have been shooting HP5+ primarily ever since.
I've dabbled in all sorts of other stuff, both film and developer, but I keep coming back to the same basic combo of HP5+ and Rodinal. It works well for me and I know what I'm getting in advance.
I do much the same thing with low ISO film, although I always waffled between PanF+ and Acros once APX100 became unobtainable, stand developed in Rodinal. These days it's purely PanF+, but I never shot as much low ISO film as I do high speed film.
I never really got into the mid-speed films. Tried them, but I always found myself preferring either a slower or faster option.