It's probably better to keep a DJ. In the past, I would randomly remember dreams, in some cases, it would be one a month or so. Ever since I started writing in my DJ and really was interested in doing so, my recall has spiked. I know remember pretty much a dream a night, sometimes two. There are cases where they are short since I don't recall much details but there are some dreams that are pretty long, so, it's a hit and miss. As for the topic at hand, well, no one really does. It all depends on self-confidence and if you work towards it. You can have LDs just based on self-confidence if you are able to really convince yourself that you will get one. Basically, get that thought out of your mind and as for your WBTB, 4-6hr is the recommended amount. I found that for me 6hr or so is the best time since I just fall back asleep at 4hr in. Good luck