Sometimes I do it in one sitting, sometimes that's quite long, like 12 hours or more! Other times I will revisit it over days or months - You'd be surprised how much thought and transformation can go into 192 characters. It depends how much potential room for improvement it "feels" like there is left, you get a sense for it, sometimes you just know it's done, others you're never quite sure when to stop trying to push harder.
I've commented in a sibling my experience live streaming which was interesting. Another Demoscener who has given this far more concerted effort on Twitch is KilledByAPixel, I think they are recorded somewhere maybe on youtube. My two attempts are lost to time.
As an example (yes shameless plug) I wrote this one recently over a couple of long evenings, I'd estimate 8 hours maybe:
But there are some familiar micro-raymarching techniques I've already developed and reused in this. The bit that took most of the time in this one was figuring out how to fit binary search marching that was required to support large differences in marching distances and textures without producing excessive moire effects.
