As the title states: How often do you flush your brake fluid?

I for reference try to do it once a year on my 87 190D but sometimes I end up going closer to 2 years.

I use a mighty vac to get it out of the resivoir and then use a pressure bleeder to drive it through, I used MB dot 4 plus (cuz I had it - not because I always need MB fluid).

Beyond the poll, I welcome any post about fluid/method/whatever.

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1987 190D Turbo (W201 602)