Well FWIW there are somewhat reproducible techniques, I've used them, but I couldn't tell you how I've used them if my life depended on it (honestly, brain chemical imbalances or fatigue might be a prerequisite). I actually got tired of lucid dreaming and started avoiding certain positions in bed, and started shifting around if I felt myself getting close to jumping into a lucid dream during hypnagogia.

I also worked on university assignments during lucid dreams, solved countless bugs in my code while asleep, a friend can even attest to it since one time I instantly woke up to solve a specific bug and then went back to sleep, with him right next to me (all nighters woo hoo).

It can be done. It really shouldn't be done. The reason why I grew tired of lucid dreaming is because I didn't feel like I was actually resting at all. That disconnect and peace that falling asleep gives you, it's not there for me while lucid dreaming (at least not if I jumped in through hypnagogia).