n=1 and all but ketamine is the only med out of 30+ that I've tried for my TRD over the last 40+ years that actually helped me long term. Every other med either had side effects that were worse than being depressed or they just didn't work beyond the first few weeks which I attribute to the initial placebo effect.
What I try to stress to people who ask is that ketamine is a powerful agent of neuroplasticity. So, so many people expect to take a pill and just feel better. With ketamine, you have to stay as positive as you can before, during and for days afterwards to reprogram your brain to be more positive. The people that I know that have had success with ketamine are those that either had therapists working with them during or right after the experience, or those who followed the "must work hard at being positive for 2-3 days after taking ketamine" advice.
This is a med that I suspect you could actually damage yourself permanently if you just take the med and then go right back to doomscrolling social media or something similarly negative. The initial experience can make you feel better for a day or two, which is huge because no other antidepressant has that kind of quick impact. But if you work at it during that 2-3 days after, you can become a more positive person permanently.
I'm hoping that it gets more accepted over time and can be prescribed by psychiatrists because compared to most other "here's some pills, hopefully you'll feel better in 6 weeks and if not, we'll give you more pills that will hopefully work in 6 weeks" depression meds, it works really fast. For someone on the verge of suicide, it can be a truly miracle med.