The only 10 gauge wire in the window system of a factory power window car is from the battery to circuit breaker which was mounted on the wall behind the left kick panel. Then 10 gauge from the CB to to the drivers window switch, all other switches worked off that power and all remaining wire was 14 gauge.
The system never maxes out at 40 AMP, the breaker would 'shut off power' when the motor reached its travel limits and then reset once you released the switch.
With all that said, you dont have a factory window set up and how your system works can be drastically different.
If your system runs off a 40 amp fuse and you keep popping it, there is a fault in the circuit, either a motor drawing too much or whatever the failsafe is when the motor reaches max travel is not working.
My suggestion is to get into the door wiring, so you can run the motors off a stand alone power source, most of us use a cordless drill battery to run window motors for testing. test each motor individually and see how they operate and work your way backwards. Hook your power source up at switches, do the switches perform just as good as directly to the motors. If not your switches are bad, then step back to the fuse connection and jumper that. applying your power to the window side of the fuse and ground the frame and see how the windows work. Its the only way to systematically figure out which link is the weakest in your set up.
Someplace in your set up there has to be some 'safety' that when the window reaches its max travel, the motor shuts off. Either internally or externally. something else to consider is when your fuse pops, as soon as you try to move, or when you reach max travel or somewhere in between. Is it just a specific window or direction causing the problem. Are the window tracks clean and does the window have the best chance to move up and down smoothly