Moving targets should of course be harder to hit than stationary ones. Well, provided you're not moving in a constrained and predictable trajectory. And you haven't just left some perfectly good cover to do so.

Fortunately in such situations you're usually only being shot at by faceless NPC mooks.

Transcript

Luke: All right, hold on. But promise no more kissing.
Leia: Aww.
Luke: I wipe the slobber off my face and we swing across the chasm. 7.
GM: You begin swinging. The troopers fire at you.
[SFX]: Pow! Pow!
Luke: I evade!
GM: How, exactly?
Luke: Uh...
R2-D2: Meat shield!
Luke: What? Princess getting lippy with me is no reason to fail this escort mission.
Leia: I'm just a mission to you?
Luke: It's kept you alive this far.
R2-D2: Hmm, valid point.
GM: You make it safely to the other side.
{beat}
Luke: You can let go of me now.