I wonder how much the "recharge while alone" feeling is due to the fact that introverts feel a need to put a front and think their every move during social situations thus making the situations unfulfilling and tiring while also making them very difficult to navigate. I find that using logic and conscious thought instead of instinct for things like social situations makes you react much more slowly to the flow these situations usually have while also making you less spontaneous and making the socializing tiresome. Maybe because we evolved to be sociable before we evolved conscious thinking and thus we have fine honed instincts that shouldnt be overidden by thinking for these things? Who knows.