This would be for things like the "8052 computer" that grew to 170+ messages, perhaps Phillip Gallo's '51 video page (were he to be interested in making it a community effort), etc. In this case the "multiple forums" would be buried in the link to each project and each forum would only be to discuss that project
My $0.02
Often, in a thread that I have no particular interest in, an issue comes up that say "ding" to me. In that case I post the thought. Also, sometimes I see something, in a thread of no interest to me, that I find useful for something else. This would be loost if you farmed 'projects' out to separate fora.

Erik