In General, How Often Should A Brake System Be Flushed?

After doing some research, I'm finding that everyone has a different idea in regard to how often to flush a cars brake system. I'm sure that some cars might differ from others, but in general what is a good rule of thumb? Please vote and let's see what most people say....

I see no reason to flush brake fluid, unless the system was contaminated or the fluid has become extremely dark. This is usually caused by people not opening the bleeder when replacing pads and forcing the dirty fluid back up the lines when retracting the caliper pistons. I believe this is just another service shop money maker.

There is no factory recommended flush interval because it is unnecessary as regular maintenance.

Same suggestion on this one. Never or not needed option.

Poll edited to add Never and we limit the poll to 90 days.

Since you added it, I voted it....Never!

I'm gonna have to agree...this is just a service shop money maker

Never got the vote for me!