Well, it ain't rocket science. In a nutshell, he's just saying "GET OUT AND SHOOT MORE!". The rest of it is just subjective opinion of the best way to do it. It certainly wouldn't make a difference whether you used an SLR or a rangefinder, I don't believe, let alone whether or not it's a Leica. Though, as a short term investment in self training, his comment about the Leica holding it's value is right.
I do believe that discipline is important. My periods of best improvement in photography are when I shot for regular photo projects (like the newsgroup "shoot ins" or the weekly projects here). And Bluebird is right, a good part of the improvement came via decent, thoughtfull feedback. Still, self evaluation is always important. "Damn, why didn't I notice that pole behind the subject before I shot!" 🙂
Cheers,
Steve