...and of course, the more you turn/true the rotors up, the more material
you are removing off the rotors, the quicker they'll warp on you.  I had the
same problem on a different vehicle, but this was a known problem with the
car.  Every 25K the rotors would warp (and this was a passenger vehicle,
never towing anything).  I solved the problem after getting new rotors by
replacing the pads when they were only half way worn down.  Thick pads,
thick rotors = better heat dissipation.  Are both rotors warped equally, or
is it more on one side or the other?  As it's not a know issue with your
truck, and if it's only one rotor that it keeps happening to, there is a
chance you could have simply gotten a bad rotor (poor material/heat
treating) and cutting it is only going to make it worse.  Other than that,
I'll let others chime in...

Good luck...

IYM

My F-250 has 60K miles and is in need of its fifth (as in 5) turning of the
front rotors. No one I know with this or a similar Ford has had anything
like this problem. The front brakes start chattering within a heart beat;
its 's not something gets worse over time. It has happened when going
downhill pulling my 5th wheel, and has happen with just my ATV in the bed
(appx 600 lbs).  Mr. Goodwrench at the local Ford dealer sez there is
nothing wrong other than I am improperly breaking. BS in my opinion. As a
bit of background, when the truck was new (less than 10K miles) I had the
ABS system light come on on two occassions, both times while just driving
down the freeway and not using the brakes (or had not used them for a long
period of time). Each time Ford said they could find nothing wrong, and
reset the the on board error recorder to 0.

My non-technician solution was to get some high performance rotors and pads.
The high performance shop is more than willing to sell me some, but it is
their opinion that there is something going on with the ABS system or
proportioning valve. Maybe the early on ABS light is a clue?

Anyway, since my local Ford dealer seems to know nothing beyond turning down
the rotors again, and again, and again; it doesn't seem likely they are
smart enough to diagnose a possible ASB problem. Is there a way I can
eliminate or confirm there is a problem with the ABS syetm?