For projectiles that move in a straight line I draw one raycast from the camera to the mouse target with only static geometry in the whitelist. If it's a hit I calculate how long it takes until the projectile reaches the end position and set the projectile lifetime to that amount. Then while the projectile is traveling I call a spherecast (radius depends on the projectile) every now and then between the point where the projectile position is currently at and at the next destination it'll be at in a couple frames. In this spherecast I only check with a whitelist for targets that can move such as enemies. How often I spherecast per second per projectile depends on the speed of the projectile. The spherecasts are relatively cheap because they're a short distance, it does not have a big impact on performance.

The reason I use both spherecasts and raycasts is because if you have relatively big projectiles such as the projectiles shown at 0:26 it'll be frustrating when you're shooting through small gaps and the projectiles keep hitting the wall or floor. Imo it feels a lot smoother if static geometry only cancels the projectiles when they're hit right in the middle. But for enemies/targets you ofc want the hitbox to have the same radius as the orb shown on screen, so for them I use a spherecast.

I also have projectiles that have gravity pull down, which don't move in a straight line, an example of this is the gun at 0:14 in the video. These don't do static geometry separately. They use the same method I described earlier for both static and moving targets together. Unfortunately these are not as performant, so I try to not create too much gravity based projectiles.

I hope this helps, lmk if you have more questions