Its not clear to me that this is generally worthwhile, even if it is very cheap per-shot; 6 targets at ~100m/s are already enough to overwhelm if the laser gets

Its not clear to me that this is generally worthwhile, even if it is very cheap per-shot; 6 targets at ~100m/s are already enough to overwhelm if the laser gets to engage those targets over 2km of their flight path (with a 4s dwell time). If your laser emplacements are somewhat expensive and only lightly armored, you might end up in a situation where your opponent happily throws cheap drones, 10 at a time, straight at your defense and still comes out way ahead financially. Israels situation is quite unique in that it is very small, but gets exposed to imprecise indirect fire a lot, so what works for them might be a really bad investment for the restt of the world.