Yeah definitely! I don't trust that my writing energy nor my memory will continue into the future, so I have a few tactics I use:
If an idea flashes into my head, I quickly write it shorthand anywhere. See my other comment (https://news.ycombinator.com/item?id=36726680) on having 'Streams' pages that offer an immediate working space to write. I let the idea expand with that progress & velocity, and once I've reached the end of my writing juices, if it's important enough I copy/paste it into a better place. Organizing is one task that can be done when the winds of flow state calm.
Similarly, breaking ideas into small bite-sized parts helps because those are easier to complete with less energy. Better to make incremental forward progress than keep trying to do the same big thing over and over.
Also, I try to start with a summarized version of what the thought is. Again, shorthanding the key points is helpful. It's easy to have a big thought that has several constituent parts and immediately dive into some details on one of those parts, only to find that the big picture sort of disappears. Better to capture the TLDR first.
Finally, I'm okay with abandoning ideas, I trust that the important ones will come back, and I make sure to leave affordances for myself so I can always return to what I was doing later. Some things I do to make revisiting ideas easier include:
1. I'll review my 'Passing Thoughts' stream at least once a week to see if my new context or a new perspective allows for the ideas to come back.
2. I keep track of work-in-progress work with a #WIP tag and new pages I've made in 'What's New' stream.
3. I keep track of my thought process with occasional self notes in 'Whats New', e.g. "I dove into X by expanding Y and Z but think I have to reorganize section A to fit it in"
4. In the organizing step I think carefully about how I name pages (including using aliases)
5. I densely link all related ideas so there's many ways to find them.
That's similar to how I organize my ideas as well. I personally use google keep for this, or just plain text files. I don't try too hard to connect them, maybe I should though.
What I do is: Not feel in the slightest guilty about it, because I just came off a stretch of real 10x productivity, and then go do something else for a half hour or so that exercises a different part of the brain - grab one of the many musical instruments around me, for instance.
Whatever point you had, whatever drive was there, is just gone. The wind has calmed and the sails just drop loose on the mast.
This happens to me, both in my own work, or writing something like this, and then I just dump it.
Kind of aggravating.