DR911s

I've experienced the same problem, and once made the huge mistake of parking my car for a couple of weeks after washing it and driving a couple of miles while frequently applying the brakes to put some heat in them. These were after market StopTech ST-60 brakes including their rotors and their own brand of high performance semi-metallic pads. The result was so much pitting of the rotors that it never went away, even following a couple of on-track sessions; instead, the pitted areas where the rotors had been parked too long in contact with the wet pads produced pulsing of the brakes and judder in the steering wheel when on track or snubbing from high speeds. I tried removing the rotors and thoroughly sanding them using a Festool Rotex machine [orbits while positively driving rotation of the disc] using various coarse aluminum oxide and "ceramic" abrasives; that helped but wasn't sufficient. I had to have the rotors turned, and the automotive-oriented machine shop found it a challenge to mount the rotors with their aluminum hubs and to dampen the vibrations in the disc while turning them since the rotors and hubs connections are designed to allow the rotors to "float" relative to the hubs to compensate for thermal expansion. New rotors then were close to $800 each. After that experience I've learned to NEVER park car with my freshly washed brakes more than overnight. I've also learned that if you have the car in a garage with a level floor, if you leave the e-brake off and the transmission in Park, you can and should attempt to move the car back and forth every few hours for a couple of days. That will redistribute the water on the rotors and facilitate complete drying and avoid seizure of the rotors to the pads via galvanic corrosion. Where I live in a hilly area in NE Ohio they apply so much road salt that it is still seeping out of some of the streets, some of which are real brick, even in late September; in other words, the roads are seldom if ever truly salt free. That salt together with the water from washing your car with a hose, is certain to aggravate the galvanic corrosion chemical reactions between your brake pads and rotors.

Unless I am going to drive my Porsche for several miles after washing it, I much prefer to use a rinseless wash technique to clean my car including the wheels after a road trip. That entirely avoids any seizure of the rotors to the pads, although it is likely to result in a light surface rust layer appearing on the outside faces of the rotors if you spray the rinseless wash chemicals onto the rotors. I avoid doing that and use a microfiber cloth drenched in the rinseless wash solution to wipe the brake dust from the wheels and calipers. No issues whatsoever with pulsing or judder after 32k miles and several track events.

rchaas

I spray a little Hyde's rust preventative on each rotor after i'm finished rinsing the wheels and then blow dry the wheels with my Ego blower. Then, a short drive and no parking brake. Also, sometimes after the drive, i'll use some detail spray and wipe down the wheel barrels.