Well, certainly a lot could be said for whatever makes you happy. For some, constantly tinkering with flight simulator is going to be part of their enjoyment of the product, just like some people spend more time working on a car than actually driving it. One could argue that FS being open to further development by the community, a certain portion of the game is about tinkering with its overall function.
The amount of time that a person spends on adding or changing components of FS could vary over time as well. There are times where I get the urge to add aircraft like crazy (usually after I have seen one somewhere that I just have to have . . . which then leads to adding a whole lot of other aircraft that I see in the downloads section that I happen across along the way). Then maybe I will go several weeks just flying the default Cessna's. I know for awhile I was continually trying to find better water and landscape add-ons. I am pretty happy with the water now and the landscape add-on I have is fairly OK. But, after so many hours of trying this or that add-on and then having to set everything back to normal when I didn't like it so much wore me out, and I went back to flying. It all comes and goes.
I wouldn't worry to much about figuring out how your time gets divided up. Just go with your own flow. At most, ask yourself what it is about FS that you like the most and then do that the most. Speaking of . . . time to go fly a plane!
Have fun!
~Darrin

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