I've never done any of this specifically myself, but as an electrical engineer the theory works like this. Your detection system will isolate as to which block a specific decoder is located in. It cannot tell you where within the block the decoder is.
So you want to set your blocks small enough so that you get the granularity of location you want. The disadvantage to small blocks is the added expense of additional detectors and extra wiring. The beauty of DCC is that block size need not have any impact on your train or locomotive operation.
More important than the actual track plan is what the use of your detection system will be. Is it to drive signals, or will it be used for automatic (software) train control? Driving signals for trains under manual (operator) control does not have the same criticality as automatic train control where logic and position errors at critical junctions can cause crashes.
Due to the multiplicity of relatively short routes, this would be a difficult layout to program for automatic operation, and would require at least 4 detection blocks on each route that will have more than one train on it simultaneously. If you don't mind signals occasionally being out of synch with the situation, you can get by with many fewer detection blocks to just drive signals.
Hope this helps
