On my guided Alps tours switchbacks and tight turns are a constant part of the riding. Depending on the number of passes and length of riding day I can easily do 200+ switchbacks/U type turns a day. I never really had a technique - just sort of learned to deal with it until I could go around most of them no problem.
Then I had a bad accident here in NH back in Oct 2014 - had surgery to reattach my broken left arm and reconstruct my left shoulder. I was left with some motion impairment and couldn't ride for 7 months. My first serious ride was back in the Alps on my June 2015 tour. I immediately realized I was in deep trouble on the switchbacks because the left arm had no strength, plus a slight jolt of pain when trying to push out to counter steer or turn to the right. Fortunately I had owned an older Ducati in a previous life, which had no turning radius and had learned to do tight turns with the Duc by simply letting it fall into turns and then picking it up with the throttle when I was far enough around. Not the most efficient or easiest way to turn - required a fair bit of constant concentration, but it got me through the June tours.
When I came home I got serious about my turning technique. I watched a bunch of videos - Ride Like a Pro was fairly informative - and I would go for a 45 - 75 minute ride every rain free morning with approx 3 - 5 parking lots along the way. I would pull into the parking lots, practice u-turns, figure 8s, friction control, etc. I did that every day for 2 months until my September Alps tours.
The upshot was/is that I can turn better now after all that deliberate practice than I ever could before my accident, even with 20 years of Alps switchback riding. Left hand turns used to be my worst, but now they are my best because I am right handed and the right arm has the strength to immediately push with no hesitation. Right hand turns are not quite as tight (although still better than before the accident) because there is usually just a fraction of hesitation, weakness, discomfort when pushing with the left arm so it takes just a tad longer to initiate the turn. I've done a number of u-turns since my practice on local roads, even 2-up, that I would have had to stop and back up on pre-accident. Who knew?