This really is a great thread. Throughout my investing career I've really struggled with the question, "When do you have enough information to make a decision." I've found myself getting "caught in the weeds" reading about things that have little value in the decision making process. I also think its a bit overwhelming for novices reading 10ks and so-forth because of all the legal jargon. You learn quickly that 10ks and other filings are all laid out in a similar fashion. With practice you'll recognize what can skimmed or skipped entirely.
When Weschler and Combs were on CNBC several months ago, Becky Quick actually asked the question I submitted surrounding this topic. I've attached the transcript which you can read for yourself.
To paraphrase, Weschler and Combs said they both look at basically the same things others have already mentioned (corporate filings, trade magazines, transcripts, etc.). The amount of time they spend is another story. Weschler actually said he'll spend 500-1000 hours researching. That seems crazy and perhaps is in need of greater context. I've also heard Wilbur Ross explicitly state that his firm usually will follow a business for several years before making an investment. Conversely, I believe Monish Pabrai has said a few days of solid research on an idea is adequate for him. And Buffett is famous for making investment decisions in mere minutes.
This is a curious topic however. Clearly the more time you spending investing, the more efficient you get with your process and decisions can be made much faster (this is what experience is all about). This is where Buffett's "compounding knowledge" comes into play. I think you also have to be very careful reading into things like Weschler's "500-1000 hours" proclamation. What is he really talking about when he makes that statement? For most companies, does enough relevant reading material even exist to spend that kind of time on?
I've learned that you just really need to do what works for you. It seems that at some point in the research process, additional information can just become a distraction from the basics of investing: What is the approximate value of this asset? Can I get it at a discount/reasonable price?
CNBC_transcript_of_Weschler__Combs_investment_process_answer.docx