It's common to distinguish between "psychedelics", which primarily function via serotonin receptors, and "dissociatives", which primarily function via NMDA receptors.

I’ve heard that Ketamine is a psychedelic deepener more than a psychedelic on its own. Ie, a little ket addition is similar to taking a much higher dose of psychedelics (but short duration): high definition mental imagery and expanded external visual effects. With a good set & setting, that combo nearly guarantees a mystical experience.

Not very long necessarily. You just need to be primed