LEFT SIDE#3: No fuses yet. That's why I left each 6924's BLUE WIRES a bit longer wired with BLUE NUT.
I'm more concerned about fusing the Right side J5 terminals used for power routing. As the wheels move through the power routed switch a dead short will damage the relay board.
----- Can I put a fuse between KW power and my MTH Buss Board.....1 fuse at the beginning of whole thing.....OR.....
Fuse before J1 PWR for EACH 6924? I do have switch motor circuits fused separately, which, as Steve mentioned, protects the switch motors. One of the original problems, was stuck buttons, that fried the switch motors. The time out feature, that is built into the 6924 board also protects the switch motors from burn-out.
J5 terminal(s) used for power routing. This definitely needs fuse protection, track/wheel/derails on a power routed switch can damage the board. The Atlas diagram shows the (3amp) fuse.
Per my post, I'm running a PWR BLUE LINE and COMMON YELLOW LINE from each MTH Buss Board post(s) over to each 6924, combining all the BLUE wire's for each board with BLUE WIRE NUT. Am I over wiring? No, you are doing fine. 
I.E., should I be just daisy chaining all these BLUE POWER wires with a fuse before each J1 PWR?
(1.) J1 PWR, only supplies power to the Atlas Switch motor, through the 6924 board.
Fuse protection here is for the switch motor, to inhibit burn out.
(2.) J6 COM/PWR supples power necessary for the board to operate and if you use dwarf lights via the J3 terminal it would also power these dwarf lights.
Fuse protection here protects the board and the dwarf lights.
(3.) J5 terminal, used for power routing.
Most important fuse. The nature of moving wheels through a switch/dead rail section is not a refined accurate art form, at times, there are short circuits here, if power routing is used. I have experience burned traces on the 6924 relay boards associated with the J5 terminal and power routing, the reason for adding the (3 amp) fuses shown on the Atlas diagram.
Best wishes
and again a very good job.
Mike CT.
