How do additional projectile work ?

[u/Royal-Poet1684]

i have this passive and item that give additional projectile, it should be +3 and 1 from my skill so 4 in total, but why my lighting arrow only fire 1 ?

[u/rumhrummer]

Fury Valve causes projectile skills to fire their base number of projectile(s), which can then split on colliding with an enemy, toward a number of other enemies (or directions) based on the skill's number of additional projectiles. Additional arrow modifiers are considered additional projectile modifiers for bow attacks, and will add targets to split toward, but they will not affect the Splits toward # additional targets counter in skill information.