Well, here are my test results:
I loaded up an L99 Assassin from nobbie's library in players 8 Nightmare. Assigned 1 skill point to Shock Web and Blade Fury, maxed out Fire Blast (increase Shock Web missiles), Blade Sentinel (for duration), Cloak of Shadows (helps testing), and Wake of Fire & Inferno (for damage). I raised my dexterity to 150 for a 95% chance to hit Zombies in the Blood Moor. Purchased a Gladius of Pestilence from Charsi with 50 poison damage over 5 seconds.
Test 1: Shock Web alone
Found pair of Zombies, blinded with Cloak of Shadwos. Spammed Shock Web at Zombies to see how much life it would lose.
Result: Could not hurt Zombie at all due to health regeneration (both subjects).
Test 2: Shock Web with Wake of Fire.
Found Zombie, blinded with Cloak of Shadows. Tossed Shock Web at Zombie and quickly cast Wake of Fire next to it, then kept spamming Shock Web.
Result: Dead Zombie (4 trials each on 3 subjects).
Test 3: Wake of Fire alone.
Found Zombie, blinded with Cloak of Shadows. Cast Wake of Fire next to it to see how fast it died.
Result: Zombie dies in practically the same amount of hits as in test #2 (4 trials each on 2 subjects).
Test 4: Shock Web with Wake of Inferno.
Found Zombie, blinded with Cloak of Shadows. Tossed Shock Web at Zombie and quickly cast Wake of Inferno next to it, then kept spamming Shock Web.
Result: Dead Zombie (2 trials each on 3 subjects).
Test 5: Wake of Inferno alone.
Found Zombie, blinded with Cloak of Shadows. Cast Wake of Inferno next to it to see how fast it died.
Result: Zombie dies in practically the same amount of hits as in test #4 (2 trials each on 2 subjects).
Test 6: Shock Web with Blade Sentinel.
Found Zombie, blinded with Cloak of Shadows. Tossed Shock Web at Zombie and quickly cast Blade Sentinel at it, then kept spamming Shock Web.
Result: Poisoned Zombie on first pass of Blade Sentinel (10 trials on 1 subject). I could also hear the re-poison sound effect on each subsequent pass of the Blade Sentinel.
Test 7: Shock Web with Blade Fury.
Found Zombie, blinded with Cloak of Shadows. Tossed Shock Web at Zombie and quickly cast Blade Fury at it, then kept spamming Shock Web.
Result: Poisoned Zombie on first hit of Blade Fury (10 trials on 1 subject). The re-poison sound effect also occured if I hit the Zombie with multiple Blade Fury missiles before the initial poison duration wore off.
Conclusion:
Testing was not rigorious since I didn't mod anything, but there is no evidence to suggest that the NextDelay of one missile has any effect on that of another's. I think you better go ahead with the mod and make a believer out of me, Crystalion.
I loaded up an L99 Assassin from nobbie's library in players 8 Nightmare. Assigned 1 skill point to Shock Web and Blade Fury, maxed out Fire Blast (increase Shock Web missiles), Blade Sentinel (for duration), Cloak of Shadows (helps testing), and Wake of Fire & Inferno (for damage). I raised my dexterity to 150 for a 95% chance to hit Zombies in the Blood Moor. Purchased a Gladius of Pestilence from Charsi with 50 poison damage over 5 seconds.
Test 1: Shock Web alone
Found pair of Zombies, blinded with Cloak of Shadwos. Spammed Shock Web at Zombies to see how much life it would lose.
Result: Could not hurt Zombie at all due to health regeneration (both subjects).
Test 2: Shock Web with Wake of Fire.
Found Zombie, blinded with Cloak of Shadows. Tossed Shock Web at Zombie and quickly cast Wake of Fire next to it, then kept spamming Shock Web.
Result: Dead Zombie (4 trials each on 3 subjects).
Test 3: Wake of Fire alone.
Found Zombie, blinded with Cloak of Shadows. Cast Wake of Fire next to it to see how fast it died.
Result: Zombie dies in practically the same amount of hits as in test #2 (4 trials each on 2 subjects).
Test 4: Shock Web with Wake of Inferno.
Found Zombie, blinded with Cloak of Shadows. Tossed Shock Web at Zombie and quickly cast Wake of Inferno next to it, then kept spamming Shock Web.
Result: Dead Zombie (2 trials each on 3 subjects).
Test 5: Wake of Inferno alone.
Found Zombie, blinded with Cloak of Shadows. Cast Wake of Inferno next to it to see how fast it died.
Result: Zombie dies in practically the same amount of hits as in test #4 (2 trials each on 2 subjects).
Test 6: Shock Web with Blade Sentinel.
Found Zombie, blinded with Cloak of Shadows. Tossed Shock Web at Zombie and quickly cast Blade Sentinel at it, then kept spamming Shock Web.
Result: Poisoned Zombie on first pass of Blade Sentinel (10 trials on 1 subject). I could also hear the re-poison sound effect on each subsequent pass of the Blade Sentinel.
Test 7: Shock Web with Blade Fury.
Found Zombie, blinded with Cloak of Shadows. Tossed Shock Web at Zombie and quickly cast Blade Fury at it, then kept spamming Shock Web.
Result: Poisoned Zombie on first hit of Blade Fury (10 trials on 1 subject). The re-poison sound effect also occured if I hit the Zombie with multiple Blade Fury missiles before the initial poison duration wore off.
Conclusion:
Testing was not rigorious since I didn't mod anything, but there is no evidence to suggest that the NextDelay of one missile has any effect on that of another's. I think you better go ahead with the mod and make a believer out of me, Crystalion.