Honestly like 50% of the time I just politely ask if I can slot in and dudes are happy to give it up. 25% of the time it turns into a stupid drag race, and the other 25% I realize how stupid drag racing for one position is and I wait until there is a better opportunity to move up.
60% of the time it works every time! It basically never works in crits, so if that's your thing be less chill.