I am new here at the forum, but I’ve already read some FAQs and Tutorials! And I still have one more question, here it is:
How much time can I stay on a LD?
Title edited for clarification; moved from Quest for Lucidity 
The amount of time may depend on how long you are asleep, how fast you go to sleep, your stress level (stress lowers chances for an LD from what I’ve learned), and your sleep habbits. There is much more that I don’t know about that other members can point out 
There are other ways to extend how long a lucid dream is as well. One of our members, WritersCube, has a tech called the Dream Clock. In an LD, he set something like “Real time: 2 hours; Dream time 140 hours” and it expands the perceived amount of time in the dream. You’re not actually taking 140 hours, of course, but it gives the perception of taking that long, so it’s a really neat way to get a dream lasting longer than you have to sleep 