Originally Posted by von_zoom
Well, let me ask everyone - How many times have your brakes failed due to lack of fluid bleeding or changing? I have run a complete HPDE season, 10, 2 day events with the same fluid. I change fluid when I change pads and/or other brake components. I have yet to have a problem. But, I have not experienced any brake situations either since I changed to better pads and ss brake lines.
That is definitely well beyond the normal bleed interval. The point isn't that they will suddenly "fail" necessarily, but over 20 track days it is likely that you will either have small air bubbles in the lines or the fluid will become saturated with water, both of which dramatically lower the boiling point. I have personally had cars get a softer brake pedal that wants to go to the floor due to boiling fluid, it is not a good feeling. If it works for you, great, but definitely be mindful of the risk and pull into the pits if the pedal starts sinking.
What fluid do you run? Some are not very hydroscopic and can be left alone longer, although I've never heard of 20 days without bleeding/flushing.
EDIT: Based on the couple of replies after me, several E9X M3 track guys get away with your bleed/flush interval. Maybe the racecar crowd I'm used to is overly cautious or stress the brake system more?