The topic of whether to cold crash or not is an interesting topic. Bill Pierce wrote an article in BYO (Mar/Apr 2006 issue) entitled: The Lowdown on Lagering: Advanced Brewing. In that article:
“Some brewing texts recommend slowly reducing the temperature by no more than 5 °F (3 °C) per day until the temperature is at the desired setting for lagering. However, many homebrewers ignore this advice and achieve excellent results. There is agreement that in order to achieve the maximum effect the lagering needs to be done cold, with the temperature no more than 40 °F (5 °C). Many commercial breweries lager at nearly freezing temperatures, in the 32–34 °F (0–1 °C) range.”
So, in my homebrewing I have done the slowly reducing temperature method and I have also cold crashed. In both cases the beers have turned out just fine. I agree 100% with Bill concerning: “However, many homebrewers ignore this advice and achieve excellent results.”
As regards the topic of how long to lager, Bill writes in his article:
“For medium to high-gravity beers, Greg Noonan — brewpub owner and author of “New Brewing Lager Beer” (1996, Brewers Publications) — recommends 7–12 days per each 2 °Plato of original gravity. (One degree Plato is roughly equal to 4 specific gravity “points.”). For lower gravity lagers the time is reduced to 3–7 days. According to those guidelines, a 1.064 O.G. German bock should be lagered for 56–96 days, while a 1.040 American lager would be lagered 15–35 days.”
I personally utilize the ‘rule’ of 7 days for each 2° Plato for lagering my homebrewed beers.
I would recommend that the OP download Bill’s article since it is a very helpful article.