I agree with you on XPs. A team scores a 6 pt touchdown but then gets to kick the ball for another point?
There aren’t many other situations in sports where scoring gives you a chance to score more. Two I can think of are:
1. College basketball- when a team goes over the foul limit, the opponent gets to shoot a one-and-one on a non-shooting foul. If they make the first one, they get a second try.
2. Bowling- 10th frame- if a bowler’s first ball is a strike , he gets a 2nd attempt. If he gets a strike on that one, he gets a 3rd try. If he doesn’t get a strike on the first ball, he can pick up the spare and then have a 3rd shot.