As a rule, when Leonard writes a "sequel" due to the success of the movie version of his novels, the results kinda suck. "Be Cool" is the most glaring example.

Leonard is extremely hit or miss with sequels in general. Some of the "sequels" he writes do turn out to be his best books: "Rum Punch" (the basis for "Jackie Brown") was a sequel, and it's my favorite book of his. "Riding the Rap," the second Raylan Givens book, was also great. It was also turned into an episode of "Justified" in the first season. "Road Dogs" is essentially part 2 of "Out of Sight," but he waited close to 15 years before writing, and it helped.