Much of those are the same forums, only accessed from different sources [sites].
Yes and no.
There are "invisible" forums that are not on any sites top forum list and cannot be navigated to by any conventional means but when and if new threads get created in them or replies added to existing threads they scroll by on a number of sites recents posts lits.
There many strange duplications of close but not exactly the same forums. There are forums that seem to be related to one topic on one site due to their placement in the forum heirarchy and are placed in a totally different area on other sites.
There are major forums on one site with perhaps 20 subforums and sub-subforums and on another site that forum will be a lone subforum obscured deep into the hierarchy.
The dulplication of forums across the multiple topics of OS Customization on one site and object desktop on another and Personal Computing in a third site is strange. Stranger is the choice of why one particular subforum that exists on two of three related sites doesn't exist on the third.
We have the general Off-topic forum (412) that's spread across most sites but then there's also the Off-Topic forum (capital T) (forum 349) that get mistaken form one another.
The Off-Topic (capital T) forum is a subforum of the GalCiv II forum on the GalCiv2 site and also a subforum of the Stardock Games > GalCiv II forum on the Stardock but on JU is just another "off topic" forum under the Misc forum that exists seemingly in parallel. So on GalCiv2 or Stardock one would assume that that Off-Topic forum is specifically related to GalCiv2 but on JU it's just another Off-Topic forum.
Basically I tried to categorize it once and it's just so messed up I couldn't make sense of it. If you have an Object Destop forum that exists on one site with 20 realted subforums then *if* you feel you need that same object desktop forum on another site shouldn't they be compatible? shouldn't the same forum directory structure exist on both sites? At least it should be similar. In any case randomly dropping and adding a different set of subforums from one site to the next is very confusing.
Plus there are probably over 100 forums that haven't had a new post since 2005. Are they really necessary? Are the "invisible" forums necessary?
Obviously this forum structure has grown over time and simply evolved without a whole bunch of thought and planning about how the directory structure should look.
If you take an honest look at it you will have to conclude that's it's simply a mess. Last time I checked there were over 755 forums spread over 12 sites of which 393 forums were unique. I'm sure it's worse by now.