Yes, over the years, I’ve experimented with many aspects of self development or spiritual development while lucid dreaming.
I think that it’s possible to carry any practise, skill or goal you wish to accomplish into sleep.
The extent to which the efficacy of the practise is carried into your waking time is interconnected with the extent of your grasp of the subconscious, intuition and awareness in your sleep.
For example, if you’d like to learn a new skill: Tapping into the concepts underlying it, accessing the concepts within your subconscious, intuition and awareness that are tied to that.
Practising grasping those concepts in dream form, understanding and changing them as you would the deeper layers of your mind, is far more effective than only reproducing the act of practising the skill ‘physically’ in a dream.
Combining both together is much more effective, and carries anything you might wish to develop into your waking life better, in my experience.
I’ve found the mind and subconscious work easily with conceptual thinking within dream states, even lucid dreams, so it can help to learn to grasp the interwoven concepts within what you’d like to develop in both waking and dream states.
This applies to things which might be considered energy or spiritual development as well. At times it can apply even more so, in my experience, as the interwoven concepts and underlying essence can be easier to access.
I think that working with one’s conceptual mind and the deeper layers of it in dreams can be of value, no matter what one’s goals and path might be. Even if one’s goals are not ‘spiritual practise’, one can still develop more flexibility and wisdom through doing so.
Working with dreams for development is an important aspect of many traditions, so I think it can be done skillfully to carry most any practise, skill or goal we experience in waking into sleep.
As @Maoshan_Wanderer wrote in another thread:
Here is one flexibility practise from an article about dream yoga:
With dream yoga, instead of using your mind as an entertainment center, you turn it into a laboratory. You experiment with dream meditations and study your mind using the medium of dreams. For example, one dream yoga practice is to change the objects in your dream. You can turn a dream table into a flower or transform your boat into a car. You can also add or subtract things in your dreams, or shift their size: expand a home into a mansion and then shrink it down into a dollhouse. Why would you want to do this? Tenzin Wangyal says:
Just as dream objects can be transformed in dreams, so emotional states and conceptual limitations can be transformed in waking life. With experience of the dreamy and malleable nature of experience, we can transform depression into happiness, fear into courage, anger into love, hopelessness into faith, distraction into presence. … Challenge the boundaries that constrict you. The purpose of these practices is to integrate lucidity and flexibility with every moment of life and to let go of the heavily conditioned way we have of ordering reality, of making meaning, of being trapped in delusion.