Since I own several old MVs, several old British Sports Cars (well known as being prone to leaking ALL fluids), and various other toys & pieces of mechanical equipment I have come to believe that you cannot check fluid levels too often.
This is especially true when you have a single circuit braking system on a vehicle as large as an M35!
I need to dig up and post a picture of my M35 parked nose-to-nose with one of my BugEye Sprites (for those unfamiliar, this is a very small sports car, similar to an MG Midget). One look at this picture and you quickly realize who would "win" if these two vehicles ever collided. There would be little left of the BugEye, the car's occupants would very likely be severely injured, and the Deuce would probably just need to have the Rockwell axles repainted!!
Given the fact that the stock Deuce Brake M/C is a PITA to check I think that installing a remote brake fluid reservoir is possibly one of the best safety improvements we can make to our trucks!
Check your fluids! & check them OFTEN!
This will save you money, will prevent unexpected failures, and might save a life!