Question about length of fermentation

I recently took a tour of the New Belgium brewery and I've seen some videos of other breweries (Stone has a really great video on their site). On the tour at New Belgium they said that their longest fermenting beer was Fat Tire and that took 14 days. Most of their others took 7-10 days the guide said.

On this forum and many other places I've read people recommend leaving the beer in the primary fermenter for up to a month and letting it sit in the bottle for several weeks.

Why let it ferment for so long when these established breweries don't and they obviously turn out a great product?

I think it's related to the techniques they use...these large professional facilities can precisely control temperature, pressure, amount of yeast cells pitched etc. etc. and they're able to more efficiently process the beer, whereas at home you're overcoming any number of deficiencies depending on your setup.

I've seen guys on the forum who are turning around beer almost as fast as the big guys, but the general consensus seems to be "when i doubt, wait it out"

Jamail has an article in this months BYO that explains that even the size and shape of fermenters have effects. We're doing 5-10 gallon batches in plastic or glass. They're doing 100s of gallons, in jacketed, stainless steel fermenters with precise temperature control. Most times we are pitching woefully inadequate yeast cells also. They are pitching on active, appropriate cell-count slurries. That's what makes homebrewing so interesting, you have to control the variables much more with small batches. Especially temperature and yeast amounts.

These breweries are having to push the beer out quickly to make money. They are pitching at optimal rates, with healthy viable yeast, properly aerated wort, and under exact temperature controls. With these capabilities they can push the beer out the door quickly and at a high quality. Conditions at home are typically less than ideal, so it is a good idea to let the yeast spend a little extra time to do its thing and clean up byproducts such as diacetyl. I'd rather give my beer an extra week in fermentor, letting it ramp up in temp as activity slows and then doing a proper cold crash rather than rush the process and risk off-flavors.

You can turn a beer very quickly at home with the right yeast and setup. A highly fermentable, medium gravity (1.045 - 1.055) wort that has been oxygenated correctly and has had a large amount of yeast pitched can complete fermentation very quickly. You can also speed up the process by cold crashing your fermenter just before kegging. I have gone from kettle to keg to glass in around 8 days in a pinch. However, i have found that leaving a batch in the fermenter for at least two weeks, preferably three (depending on the yeast strain of course) leads to better beer. I have also found that letting the beer cold condition in the keg for two or three weeks helps to clarify the beer and ultimately leads to cleaner tasting beer.

If you bottle with priming sugar, you have to let the beer sit in the bottles at room temp for at least two weeks in order for the beer to carbonate. Cold conditioning after the two week mark for several days does improve the flavor though. Try two bottles of your homebrew, one cold conditioned for 3-5 days, and one chilled for 3 hours. You will notice a difference.

Another aspect to consider is that the pro breweries usually filter their beer which also speeds up the process.

If you want to turn a beer quickly, try pitching two packs of Safale -04 (or a similar amount of another highly flocculant yeast strain). Just wait for the krausen to settle and bottle / keg.

In general, a lot of inexperienced brewers want to make things go faster. In time most realize that patience leads to better beer. Especially since we don't have all the bells and whistles that a pro brewery has to speed things up.