But that isn't really true.
When it comes down to it, the full count is 96. You see, 19 of the plans contain insets showing the surrounding region (at a smaller scale than the main town plan), while 12 offer an even larger scale mapping of the town center. Some contain both. Another 12 are ground plans of museums, churches, and fortresses. And all of this is in addition to the 39 proper maps, which are listed separately.
In a nutshell, the Handbook is full of plans.