Ricochet and spark (chain)

On wiki I read this so I'm confused.

A projectile cannot chain to a target it has already hit. If a skill produces multiple projectiles, none of those projectiles can chain to a target which any of them have already hit.

Now what ricochet say is:
Projectiles have 30% chance to be able to Chain when colliding with terrain.

Does this mean as long as projectile have hit target it can never chain to it or does it mean if one have chained it can never do it again or all other projectiles as well?

I find it strange to be so useless or am I'm missing something?

Spark is a bit of an exception, because it can hit targets a second time after a delay of 0.66 seconds (someone can correct me on that number if it is off).

The other exception of Spark is that it always bounces off terrain even without the Deadeye's Ricochet node, so I do not know if it could even "consume" the chain that way.

I doubt that having it chain would prevent it from hitting the same target if it had been long enough for the target to be hit again.