Never. Launch day switch with original joycons.

Three pairs, every 10-11 months. Have a pro controller now so I don't use them that much anymore. Hopefully it doesn't happen again.
It usually starts of very weak, just a little bit and then gradually gets worse and worse. After being tortured for a month or so I'd usually just replace them.

This should have been fixed long ago. Nintendo's  ignorance towards this problem is inexcusable.

I have. Sent them in and got em fixed for free.

Hope Nintendo fixes all of them for free and hope any class action lawsuits are successful: should have never happened to begin with.

Three out of my four Joycons drifted. It was very annoying, I'm not gonna lie. But there is a simple fix for it, you just need some contact cleaner spray. Beneath the thumb pad is a small circular black plastic lid. You can try to carefully lift this with some tweezers and then you should see a grey stick attached to a round joint. That's where dust particles probably have settled, so aim the contact cleaner there and give everything a quick burst from multiple directions. Rotate the sticks for a minute to let the spray reach every parts, then let it dry for a couple of hours. Fixed. It also certainly helps to recalibrate the sticks afterwards in the systems menu when everything is said and done.

My original right Joycon also had an issue with the r-button, it stopped recognizing inputs and this got worse over time. That was also very annoying, but I was able to fix this with the same method as well.

I have had five Joy-Con with drifting, two pairs and a left unit. I use my Switch a lot, mind you, but I treat it like a prince, and I never had such problems with my Wii U units and my 360.

Another frequent problem is that the Joy-Con rails become loose overtime and the controllers can detach from the console very easily. This can be solved with a case, but I don't think it should ever be needed, to begin with.

Switch is a great console, but it's a crystal-like product.

MAN, I play it when I go out of town or in the bed from time to time. 

When switch first released, I was hired at NOA to take calls in the technical support center. I had a lot of different calls but the overwhelming majority of the calls I received were for joy on drift. 

it’s a real thing. 

Yup, and you just reminded me of some rather bittersweet days. I also worked in a call center for Nintendo not too long ago, calls for Switch in general and drifting were the norm but I was surprised by how many people called regarding the Wii, elderly people and young children at that, which I guess isn't so glamorous. I hated those calls, because even though we couldn't process repair orders since support for the Wii ended long ago, we still had to go through general troubleshooting and convince the caller that we couldn't do anything. 

Fortunately I haven't so far (my NS is 1 year and a half old).

Got 3 pairs so far, got one drift on my very first one.

But know I have other issues with one (keep turning on the console and pushing random bittons), bit it's like 4 now, so I'm lile "eh, it lasted as long as it could"