I find it funny alot of people still don't know Lucio's heal boost is line of sight. They practically wasting their boost, jumping around but never focus on their teammate giving them the heals.
It confuses me to this day, because isn't the number in the center of the screen supposed to indicate how many people on your team you're affecting with your boosts?
I find that I boost plenty of team members even if I can't see them, the exception being if they're behind walls.