I'll add my anecdote to the pile. I don't use ketamine a lot (it is not very good for headaches, pretty good for dulling a mosquito bite until it fades away naturally, excellent for dancing).

I've taken about 1000mg over the course of several months, at irregular intervals. While it is somewhat higher than Scott's 280mg/month, it's not an order of magnitude higher. Certainly nowhere near 90,000mg/month.

I can report one event of pain while peeing, a few days ago. So it looks like my body is not built to handle even moderate levels of ketamine use, and I'd have to stay closer to 100mg/month or lower to be on the safe side.

That said, let me reiterate, this is anecdote. I only think it's interesting because there is no other reasonable explanation for my recent urinary pain, and I didn't expect such low doses of Ketamine to have noticeable effects.