This is an interesting topic. It used to NOT be, until I had my first taste of brake shimmy that I couldn't make go away.
I have an '06 EX-L with about 75k miles. I live on a plateau with a 600' elevation change to get to any retail services or the freeway.
Now, I also have a track car that I've maintained for the past 4 yrs with about 2-dozen brake repair/replace jobs done on mine and friend's cars.
Typically when I experience brake shimmy, it's because of uneven pad deposits. Brakes are hot, there is a stoplight at the bottom of the hill, then I rest the hot brake pad onto one spot of the rotor at the light which deposits a little more brake material in that spot. As the brakes cool and brakes reapplied, that one spot can gather more material creating a bit of grab on the one spot.
I will do a brake bedding in procedure every once in a while to evenly distribute the brake pad material to clean up the deposits.
This has worked fine with my Odyssey as I've had to do this close to 40k miles, then again at 50k. By 60k, I noticed that I couldn't get the shimmy to go away with mere bedding in practices. Probably time for new rotors and pads. Pad life good, didn't check rotors.
Replaced rotors and pads around 65k miles. Shimmy starts up again 4mos later. Went for bedding in procedure. Can't make it go away. Take rotors to shop and they confirm rotor is warped or the rotor surface has run-out outside of spec. I turn it and of course it is smooth for a while then shimmy again in about a mos. Duh...if I warped due to heat, then if I take more material away, then it's gonna warp faster.
Replaced front rotors and pads. Smooth for a while, then shimmy starts up again in about 3 mos. Can't make it go away.
I replace front rotor once again last week. Same pads. But this time, I take extra precautions of scrubbing caliper and retaining clips with a wire brush. I clean and lube the slider pins very thoroughly.
I get to the rear and notice that the rear slider pin is a bit dry. Also, the run-out from the rotor is causing it to contact the dust/heat shield. I can hear intermittant rubbing of the parking brake.
I wonder if the rears were not doing its job at the time? I blamed the fronts because that's what I could feel through the steering wheel. But if the rears were not doing its job (too much run-out, contaminated pads, etc...) then the fronts would be doing extra work and making it fail sooner.
I'm going to replace the rear rotors this weekend to see if I can make it all go away.
This is the most frustration I've ever had with brakes. I will take some of the blame as I think that on one of my initial bedding in runs (I think this is where I may have gone wrong in the first place) I put too much heat into the rotors/pads. Being a heavy vehicle with oem pads, I don't think I really needed a bedding in run. Too used to sports/sem-race pads on light cars that require proper bedding in to get them to work properly. A couple of drives down the plateau or a commute home is probably sufficient.
Obviously I'm struggling with my own lack of knowledge with maintaining a 4000+# minivan. But hopefully you can use some of this experience to build the community database.