Based on some training data from Bright Knight, this book is the next logical step difficulty wise after Bain. It contains about 60% checkmate problems, many trivial one-move problems and several more difficult two and three move problems. A few of the problems aren't usually valid in terms of problems since they call for things like en passant captures and castling. Also close to 10% of the problems have some errata listed. All of that aside, it's a good problem book for your money and is definitely more challenging than Bain. On to my results.
As expected, I significantly improved at problems that I had already seen, so I won't list any charts for that. For comparisons sake, after my 6th pass I was able to complete 74.4% of the problems in under 15 seconds vs 86.3% for Bain. And just like Bright Knight, I was able to improve on problems I hadn't seen before also.
Here's the chart showing the percentage of problems I completed in under 15 seconds for each pass.
As you can see, I was able to improve from 30-38% on the first pass of the first 3 sets to 50% on the first pass of the last 3 sets. My improvement in subsequent sets seems to have leveled off after the 4th set.
Like in my Bain revision, I identified 182 problems that I wasn't able to complete in under 15 seconds at least twice in my last three passes. I've broken these up into two equal sets of 91 and will work them like they are a new problem book. I'm starting to feel like Chess Hero is either a better tactics trainer than Anki or just better at getting accurate times. After 3 passes through my 1st supplemental set, I'm already at a 92% solve rate in under 15 seconds. And these were problems I struggled mightily with before.
My next tactics set will be Dan Heisman's - Back to Basics: Tactics and it will be done entirely in Chess Hero, although there are a couple problems that aren't really meant for solving as a pure tactical puzzle graded by the computer. I am scheduled to start that training set 2/26/2014.
The Woolum sets were 132 problems each, and I'm feeling like that might be too much when trying to learn tactics patterns. The ~65 problems per set in Bain was much easier to deal with. Going forward, I think I am going to try to keeps the sets under 80, even if it would take me twice as long to do a complete revision. Also complicating things was converting all 792 problems in Woolum into pgn format. My method up to this point had been to load a pgn into Chessbase and copy diagrams into Anki for flashcard use. That proved very time consuming for Woolum since no pgn file already exists for this book. I'm also going to prefer books with pgns out there somewhere to ones without. I don't consider it unethical in the least to download a pgn version of the book when I've already bought a copy as well. It's just making my use of the book more suitable for my needs. I guess this is making my conversion to doing software based tactical training all the more likely, but I like the old-fashioned progression through increasingly difficult chess books.