Say you could have a totally clear lucid dream, which was stable and couldn't collapse, with no chance of waking up by accident.
It would last for a long time, maybe days, but only a night would go by in the real world.

What would you do in it? 100% clear, 100% stable, 100% recall.
Make a story about what you'd do, and it might help you actually do it one night. Almost like incubating it.