In all of this, I had the rare opportunity to appreciate what I didn't know, and what no single person ever can. The beer world is so big that no single person can begin to fathom it. A comment by regular-reader Mike reminded me of how fraught this ignorance can be, and how difficult it can be to talk about a thing so big that we can't ever really know it wholly:
This is almost certainly wrong. I visited five breweries in Bavaria and none lagered their beer that long. Of the 51 I visited in Europe, I know of only two that meet Mike's standard--Budvar and, oddly, the French biere de garde producer Castelain (Ch'ti). Of the breweries I visited, four weeks for a standard 12 degree beer is an adequate lagering time. (For strong beers, many breweries do extend aging times.) The thing is, there are 1300 German breweries, most of them in Bavaria, and leaving aside the question of "good" ones, who actually has the data on this? I suspect it doesn't exist. Maybe there's a German-language book that catalogs Bavarian breweries and has run a tally, but it would surprise the hell out of me. For one: why would anyone gather that piece of information? Therefore I say "almost certainly" because it's the hedge you have to give when you don't know.
You wrote: "There and at other places, like Birrificio do Como which I visited today, they make real lagers in the German mode" and mentioned lagering time of 4-8 weeks.
While it may be true that some German breweries lager for only four weeks, most of the good ones (particularly in Bavaria), lager longer - eight weeks and longer.
There are a few general areas of knowledge in the beer world, like history, brewing techniques, aesthetic and technical aspects. To the extent anyone's an expert on one, it's just a part of one domain, and she is likely no more knowledgeable about aspects of the other two. Our beloved historical bloggers know a great deal about British brewing history and, in Ron's case, German, but how well do they know Czech or American history--never mind the chemical behavior of alpha acids, say, or the way to properly care for and nurture foeder-aging red ale? Jean Van Roy is a legendary brewer, but I wouldn't trust him to expound on the methods of making cask ale. Stan Hieronymus is now the greatest generalist in the subject of hops, but does he know ... actually, never mind. He probably does. That's the one guy who may know everything.
But the really amazing thing is that there are certain types of information that no one has, like the subject of Mike's comment. Another example: I relied heavily on one source to understand the history of Belgian beer--Georges Lacambre's famous treatise from 1851. But there are no doubt dozens of places where his generalizations about the breweries he described were slightly off. He may have failed to notice common practices or over-emphasized the ubiquity of other practices. When you read beer books now, you see a bunch of styles mentioned--all those Lacambre discussed. But even he acknowledged that there were dozens more that he wasn't mentioning. History is pieced together by the fragments we have, not those that got lost.
Anyway, I should wrap this up. I mention it all because the act of visiting breweries is invariably humbling. It causes you to touch that vast ignorance. There are so many different ways of doing things, different ingredients to do them with, and different philosophies about how they should be done that it's impossible to capture them all. (Like Lacambre, I have to winnow.) The result is averaging, smoothing, and making general statements that we hope are true. Almost certainly, some of them won't be.