For the most recent compact book, volume 4, I increased the number of puzzles from 100 to 150, because I had realised I could do so with only a small increase in selling price. But this volume has sold very sluggishly. My mistake, I suppose, was to weaken the defining characteristic of the series - compactness. The book is about 50% thicker and heavier than its predecessors, and hence less appealing to many readers, despite its better value for money.
The next compact volume, which will come out within a few weeks, will revert to the original size of 100 puzzles in under 80 pages. The consumer is king - at least in Chihuahua land.