I think it is good practice to spray the funnel with water and wipe clean before and after each use. That way, well, redundancy can be nice.
Also, as mentioned brake fluid should probably be the most segregated. Other than that, if you wish to use different funnels- maybe use one for motor oil, transmission fluid, ps fluid, gear oil and waste oil. Then maybe a dedicated on for brake fluid. Then you have coolant, ww fluid, gasoline, but gasoline should probably go in the oil section.
Way to up your skill by sweating the details. And asking. Because, sometimes it may seem harmless, aka a few drops of oil in the brake reservoir, but can ruin parts and more...