Alright, so between 10:30 and 4am is 5.5 hours of sleep... it's decent... but consider this... we sleep in approximately 90 minutes cycles. Cycle 3 is roughly 4.5 hours of sleep, and cycle 4 is roughly 6 hours of sleep.

5.5 hours falls dead in the middle of a sleep cycle. At this time of the morning, your REM sleep is longer, and it is on the close side to 6 hours, so you might actually be either interrupting REM sleep, or... you'll be waking up just before it begins.

Timing is very tricky when you WILD...

I understand it's really frustrating. WILD is a very frustrating technique. I actually don't recommend first time lucid dreamers to use it at all. Some people are predisposed to it, and can get it right away, but a vast many people come in here thinking, "OMG, WILDs are awesome because you start the dream lucid!!! " then try for 3 weeks and give up because they can't do it.

So I'm wondering, what is it for you, about WILDing, that makes it look better than the other half of the techniques? I advise you have a peek at the DILD and MILD techniques in the Wiki. There's more things that you can do, during the day, to increase your chances of having a lucid dream, and they also don't hit your sleep schedule as hard as WILDs can. Wake Back To Bed's can be as long as you like (enough to get out of bed and use the washroom, thinking about your goals and lucidity, and go back to sleep thinking about recognizing yourself in a lucid dream). It's really in the quality of time spent. The major thing is, you don't want to fall back to sleep losing your mind and losing your focus/intent of having a lucid dream.