"When the usual case is no exception, try/catch is "extremely efficient" when compared to LBYL."
that's why it's better
I don't know how you could use a try/except block as part of normal flow, unless you're intentionally raising tons of exceptions where you don't need to. there's no reason for most normal things to raise exceptions, so you wouldn't even have an opportunity to catch anything
if you're going to want to do something like respond with a 400 error, you're gonna need to "check" it one way or the other, and try/except is better