Assuming you can learn anything from the experience. What you might learn is weird idiosyncrasies and futile tactics playing from desperation. You might learn to not lose so quickly, but that's not the same as winning.
I don't keep playing lost games, I just resign. Maybe I should because I play mostly bullet, but as you say, you don't really learn anything interesting in those situations.
I do improve playing against better players than me. Like 200 or 300 this year. Maybe it's because I'm more focused when the opponent has a better rating.
