It depends on the player as well as their mood, really. If one is receptive at all to playing a character that’s the opposite of the one you normally play, sometimes it can be liberating to explore that difference, sometimes not. Ken and Sagat might have just enough in common, whereas Ken and Adon might not.
It can come down to that difference of the finer factors. Ken and Adon are both based on offense, mixups, and pokes, but you may not like how Adon has really short hitconfirms and spacing fundamentals. Someone else may like the zoning game of fireball chars, but not like how stiff Sagat’s links are. So basically, yes, you can learn stuff from stretching out with diametric opposites, but at the same time there may be chars that have something you can’t tolerate enough to consider even trying to explore for very long.
Overall, the answer is also yes inasmuch as playing one character will affect your style with another char. That’s just really part of the metagame, where playing more and seeing more situations helps in the big picture. It may help you see something you wouldn’t have tried otherwise, or it might let you figure out how where a char’s strengths and weaknesses lay by way of comparison.