I plan everything tbh.
I like hiding spoilers/easter eggs in plain sight. So I pretty much plan everything. I do wing some things but most of the time it is mostly planned.
My writing style also has to do with the lore. My POV on 1st person also has to do with the Lore. The character names have a reason. OC designs have set colors and designs for a reason.
As of right now I have 9 books planned. And all are connected. Few smart people will see the connection and why I did what I did with my writing style. Others won't realize most easter eggs till I reveal them. Which is fair I did hide them in some sort of code. (Think Gravity Falls style of code).
I did use some elements in my 1st POV that @cherrystark would absolutely hate. But they have a reason connected to the lore. Just like cherry, I know many won't like what I did which is why I'm being careful with how I use such techniques.
Nevertheless, artistically I think everyone will appreciate how it is written like that to connect with the Lore. That is just my assumption. I may be wrong but it is a risk I am willing to take.
I plan so much I have a gallery of over 6000 images with references. 
P.S. Love you Cherry but for the sake of your sanity don't read my novels
. I know many of your pet peeves.