Just from casual observation, since reading the Almanac it has upped my game. As far as being labor intensive, it's no more labor than I would have done reading something else in the same time frame anyway.
Counter question: have you actually taken the Jeopardy! contestant exam at any point?
(really don't want to take it in this direction but I have to know)
Yes, I took it in Philadelphia in 1997 (passed, but didn't get further), in Washington DC in I think 1999 or 2000, and I got to take two tests in Boston in October of 2002.
Since the incarnation of the online tests, I think I only missed one year. My scores have gone up since reading the Almanac, and although it took until this year to pass, I've been much closer in recent years. I have also passed 5 of the last 6 tests I have taken for Millionaire, 4 of those since reading the good book. The Jeopardy tests are heavy on Art/Literature and that is my weakest subject of the classic 6 Trivial Pursuit subjects. What I'm saying there is that if you were to place the Jeopardy test questions into those classic 6 categories, AL is a runaway favorite of the tests, but not this test-taker.
When watching Jeopardy at home and keeping score, my average score (straight, no betting, total score after two rounds) has gone from $14,662.79 in 05-06 to $19,859.72 this season.
I tend to retain much of what I read, and no I didn't memorize all the tables and basically meaningless stuff, but it did show me how much GM spent on advertising vs. other companies and yeah, the fact that GM is (was at the time of the 2007 almanac) the biggest spender on ads has probably come up.
One of the best things it did for me was to get me to finally memorize the presidents and most of the elements and their symbols. While I read the parts about the countries of the world, it helped me to better remember their capitals and some history. While I read that part I also made sure to look at the included maps and learn some rivers and other major cities in those countries plus the languages they speak and the currency they use.
Another thing I've done that has furthered my trivia game was crossword puzzles--lots of them. I did that before I bought the Almanac. My reason for doing it, well it got me to quit smoking after more than 20 years of lighting up! When I went on break, I would do a crossword puzzle, or read some trivia and forget all about wanting a cigarette. By the time I was done with the puzzle, break was over and back to work, no time to smoke.
To date, I have passed 28 game show tests and will be going for #29 next Friday (Millionaire).