Can anyone tell me how oftern they have LD's and how long they can make them last.

There is no use in putting so much effort into this if it is impossible to have a lucid dream longer than a fe minutes.....

are they just random freak events, or it is possible to have them consitently and be in full control and aware for a fairly long time.

I would like any experienced Lucid dreamers thoughts about what is possible....