I dunno about XTs, but XT-6s have a nice, user adjustable interval wiper
controller in them, that even speeds up the interval of the wiper based on
the car's speed, and back down again when you come to a stop and don't need
10 wipes a minute anymore.  You might see if you can find one of those.  Not
sure all the complexities necessary for hooking one in, but I'll bet if
you're clever enough, you can even get the speed sensor going.  (-;  If
Subaru had that part way back when, I don't see why it isn't an option for
their newer cars, as they already spent the R&D on it.

I've often thought of adding something adjustable like that to my Impreza.
Not sure if you would add it to the existing wiper controller, or if you
need to replace the existing stuffs with it, but that's the sort of
controller I would look for.  Last time I asked at a wrecking yard, they
said only newer luxury cars had a speed variable controller.  Is that yet
another thing Subaru put in ahead of it's time!  :-)

~Brian

I do not have those either.. as you said, they are never just right. Is
the drizzle ever so intermittent to be "just right"?
   Never thought of that intermittent being adjustable, have had that in
many cars, very rarely used it.

bay an original wiper switch with adjustable interval and replace it  and it
will work