Good to hear from you, Joe.
I have been in quite a few, but although I finish them they are rarely successful.
There is one answer only.
The host. The host. The host. The best host I ever saw was Frank (Daywalker)
He would answer every post, every day. It kept the thing alive.
Hans V H is good too for a similar reason.
A GB cannot run itself. There needs to be a constant lead on the deadline and the general admin.
The Falkland GB has been a very good one and like I say, I know of what I speak. Both the OP and a few helpers have kept it on a pace.
Joe you had a good run of PH GB's. What made those work was the constant leading posts you would toss in, every day.
The host is really the key.