I'm aware everyone's bodies and psychology is different when it comes to attempting LDing techniques. When it comes to WBTB specifically what time intervals (hours spent sleeping before waking up and length of time awake before going back to bed) have you found gave you the highest chances of becoming lucid?
I've found, pretty consistently, that a minimum of 5 hours' sleep before WBTB and a WBTB of no less than 30 minutes but no more than an hour works best for me. When WBTB is on the schedule, I also stay up until about 2am the night before.
Though you didn't mention it, another important part of WBTB timing for me is when I do them. I set aside a "dreaming day" once a week: I do extra anticipatory mental prep the night before, am careful to have at least the whole morning available for undisturbed sleep and dreams and the afternoon available to write everything down and think about where I just went. I think that finding and dedicating time for LD'ing is just as important as the rest of the stuff, but it is often overlooked. [Full disclosure: this is not the only time I attempt LD's, and certainly not the only time I have them: I lay down every night expecting to LD, and frequently have "happy accident" DILD's... but dreaming day is when I am pretty much guaranteed a LD, and when I do most of my planned work.]
Finally, yes, timing is generally up to the individual, so "sweet spots" will definitely vary and everyone needs to find their own. That said, I would imagine that most responses here will include several hours' sleep and a reasonably lengthy WBTB.
Yea for me right around an hour works best. I tried 15 mins this morning because I wanted to make sure I could get back to sleep and I overslept for my WBTB time (slept 6.5 hours) and it didn't work although I have had an LD before just getting up and going to the bathroom and returning to sleep... the chances of that happening are so low though for me. 30 mins has been hit and miss... maybe 50-60% success rate. 1 hour is 100% so far... but an hour is a long time to stay up it's like I have to set aside 10 hours of time to get my 8 hours and also factor in the hour staying up and the sometimes hour it takes me to get back to sleep. On a weekday... that is a huge pain in the butt.
Though I've only done a WBTB once, I woke up nearly wide awake. I think this is how I wake up during the night so at that WBTB I could only write down a dream and go to the washroom, and even after that I was still too awake, though I managed to fall asleep. So I think I'll be doing very short WBTBs, around 5-10 minutes.
I am an older guy so I think it varies with age and sleep needs. 4 hrs before WBTB and a very short bathroom break of 2 minutes works for me, if I have intent to LD.