I'm interested to pursue this question to illuminate the more literal vs abstract notions of the variants. Especially the sexual variant (sex vs "missing piece").
By definition/purely on principal, how would each of the subtypes approach something like casual sex? or casual relationships? (acquaintances, friendships where you are aligned because of work, school but don't really match otherwise etc)
For me, I find it hard to do anything casually. Mainly with regards to relationships. Those in the "sexual instinct purely as intensity" may say that sexual types readily jump into any encounter that gives them intensity. However, I personally am very discriminant about where the intensity is coming from, what kind it is, and whether it matches my being.
When I don't connect or have great rapport/effortless connection with someone, in any context, I end up feeling hollow. I like all kinds of people, but I really feel hollow (by my standards) with most people unless they "match" me. Which is why I find keeping friends hard. I look for this match and through that I am fulfilled by the right degree of intensity; rather than getting an oomph purely out of an 'intense experience' with -anyone-.
There are some who would seek casual experiences on the basis of pure physical attraction (looks) but i'm more of a 'whole package'/'presence' kind of person. I'm not sure whether I get much intensity fulfillment from looks alone. To me, it's about how you bounce off each other; synergy. Having sex just for fun with a "hot guy" or playful fun with a dude I don't even respect just doesn't tickle my fancy. Just like randomly hanging out with a bunch of people I don't know much 'for fun' doesn't do much for me either. I'll do it and enjoy the moment, but... it doesn't fulfill me.
I wonder if the 'it's just sex' (sex purely as a physical urge... which at the end of the day it literally is. And while I can separate feelings and sex I find it hard to be fulfilled when one is lacking from the equation) is more in the SP domain.