Never believed this because I'm strong N and don't walk around talking about theories all day. Meanwhile, a good friend of mine is strong S, and uses a lot of big words to express what could be said far more simply. While exhibiting many S traits, the last thing you would call him is "practical".
While I think it's harder to tell S/N apart than the other 3, whether someone is "practical" tells you nothing. No idea is practical if it can't be used. The iPhone, bifocals, and light bulb were all invented by strong N's, and are very practical. Difference is they required looking ahead, and this to me is the biggest distinction between S and N - S lives in the moment, N lives in the future, but you can't say one is more practical than the other.
One of the common traits of ADHD, mostly an N diagnosis, is impending doom. As an N, I can understand this, because I naturally think about how what I'm doing now will impact the future. Many NPs I know are best motivated by work that alters how people will do things in the future, even if it relates to something small - like changing how an industry orders parts from suppliers. Everything can be improved upon. Also noticed many NPs sometimes care a lot less about money if they feel their work will impact the future. Ss on the other hand will be happy making an impact immediately.
I think this time distinction tells you a lot more about S/N then whether someone discusses theories. Some of that is the result of individual experience, not innate type.