So over the course of the last few months, I have noticed a trend. We're scanning our WH system every day, writing down what all the sigs are, and updated a MOTD in corpchat with them, so we have ready access to the number of sigs and what type were there the previous day.
I had mentioned in a previous post that we hadn't had a grav site spawn in months, and then all of a sudden, we had two. What I came up with as the common denominator was that both our statics were closed for three days. Now, I can't remember if we had any inbound K162s, but I'm positive we didn't exit our wormhole.
And in that time we had two gravimetric sites spawn. Coincidence? Mayhaps. I'm going to test the theory further in the coming weeks. This may not apply to all sig types, as it surely doesn't apply to combat site types.
Of course, it may not apply to any. Maybe this is what CCP meant by the spawn rate slowing down when people live inside a wormhole. If the door is open and people are coming and going everyday, maybe a very bare minimum spawns. But if you leave the door closed, there's a much higher chance.
Only time and a careful watch of all our sigs will tell. If anyone else has any theories, share them!