I try to organize my scenes with the Swight Swain/Jack Bickman structure of a character with a GOAL, CONFLICT to that goal, ending with a DISASTER to the goal.

Ending a chapter with a big DISASTER makes it easier for the reader to keep turning pages. Ten pages just fits the way I write with that scenerio. I do have to admit that my mystrery has several 7 page chapters, allowing for me to add to them caus I know I will.