3 Spawns or 4?

Occasionally I run across a new site that I've never personally run before. So I check the alliance wiki and find out that although the site is partially documented it's not complete. The trigger and spawn patterns are not documented properly.

So I start running this one, updating the wiki as I go. Let's just say that everything is fine until the 3rd wave. Now most Perimeter sites are 3 wave sites. The 4 wave sites tend to be the more difficult Frontier and Core sites.

So I'm in a BC. and I've got the following third spawn to deal with: 1 x Sleepless Patroller, 4 x Emergent Patrollers and 4 x Emergent Escorts. Doable right? But the escorts are proving problematic and slowing me down such that I'm having issues getting under the Sleeplesses guns. So I start offing Escorts. Now I'm on the 3rd spawn and there are not indications that there would be a 4th spawn right? and even if so, the odds are only 33% that the escorts are the trigger for the next spawn.

Wrong! Last one goes down and overview fills with red... 8 more cruisers and 4 more frigates... Worse, I didn't spot the frigates initially and thought I'd taken out all the webbing frigates. For the clueless, one of the major methods of dealing with spawns is speed. Keep your speed up reduces the damage you take from missiles (including those incoming Phantasmata missiles). It also tends to reduce damage from bigger guns due to tracking if you're "under the guns". I'm still left with dealing with the following total ship count:

3 x Awakened Escorts
5 x Awakened Patrollers
4 x Emergent Escorts
4 x Emergent Patrollers
1 x Sleepless Patroller

A bit of armor repair at the POS later and some help from some alliance pilots later and that's all under the rug but still... Ouch.

Now for bonus points, which site was I running?