With the constant flip-flop, I'd say your J/P preference is about balanced and you waffle between the two depending on the situation. I do this. Sometimes I'm very 'P' in that nothing gets done and I'll just sit and think and think and think for no apparent purpose other than I want to think. Other times I'll be all over something like white on rice on a paper plate in a snow storm! The J comes out when I need to accomplish something or am under a deadline, and tends to be the (slighly) more frequent habit.
My process is I think I want to know about something, then I research the hell out of it online, then after I feel like I've read enough...i break out the needle and thread and learn to suture, or how to build a survival stove out of a can. Or whatnot. Then I obsess over it until it is learnt ( I spent 6 hours and stayed up all night sucking at suturing, then it clicked after a certain suture, i didnt even wonder if it had been a fluke. I packed the stuff up and went to the bed, and can suture like a fiend...btw if anyone is wondering its for field first aid) and then I put it in storage and find somethign else to master.
As a J, I rarely think in terms of 'skills' and 'mastery' and more in terms of projects. If I need something for a project, I'll look it up and figure it out, but really I'm going for a finished product.
-Carefully taking sips from the Fire Hose of Knowledge