my expirenses wil never be exactly the same as anyone elses but the main thing about dream lenth that I have learned is that thinking ends lucid dreams pretty. fast when people told me to interact with my dream sourondings I never once thought that thinking alot could hurt this, but it might have. Im no expert but it helped me alot to realy kind of meditate in a way while I looked at my surroundings
hope this helps someone on the dreamscape!
Being someone that overthinks in waking life, my few successes in Lucid Dreams have been fairly thought-free, other than very basic ones of what to do, I've had almost no interaction with my environment other than say opening a window to fly out and punching through some doors in a cabin once!
I'm currently trying to drill in the reality checks to be instinctual which I guess is the holy grail for reality checking...but it's so hard!
This is something I've been wondering about as well, so I'm glad you brought it up.
When I started doing reality checks I was making a very deliberate and thoughtful effort to talk myself through the steps in my head. However, I noticed myself getting too caught up in the thoughts occasionally and would deviate from the purpose of it so recently I've started trying to take a more mindful approach, and maintain focus on the present moment and just be a vigilant observer as I go through my checks.
I'm hoping this will translate into the dream state when I'm doing my checks there, because I felt like having too much deliberate thought activity might influence the dream and also lead me to get distracted from what I'm actually doing, or as you say end lucidity or the dream early.
Still testing this out though and adjusting to the new RC process but hopefully I'll see some good results from thinking about it this way.