There is actually no technical limit to the number of documents that a folder can hold in VisibleThread. However, from a practical usability point of view, we would suggest keeping folders to a max of about 20-25 docs per folder.
Why? If you stuff up to 100 docs into a folder, users will have a harder time understanding the the folder level views especially for discovery and concepts. In this example, if you have 100 docs in a folder then you will end up scrolling a huge amount in the folder level view for discovery and concepts specifically, so you can lose context.
There is a 2nd potential downside and that is load time, although that will depend on the size of the documents. To be explicit, 20 docs of 5 pages has a much lower number of discovery concepts than 20 docs of 500 pages each. These will be quite different from a performance standpoint. Again this is specific to folder level views for discovery and concept tracking.
So what if I have 60 similar docs, say for past performance? what do I do?
In this case, we would suggest splitting out the docs into 3 folders. Name each folder with a number suffix. So you might have:
=> Past Perf - 1
=> Past Perf - 2
=> Past Perf - 3
Or alternatively, we have seen customers tagging them by date like this:
=>Past Perf - 2012 - 1
=>Past Perf - 2012 - 2
=>Past Perf - 2013 - 1
And finally some customers name folders by customer:
=>Past Perf - Navy
=>Past Perf - Army - 1
=>Past Perf - Army - 12
But then I wont be able to search all docs at the same time, is that not a problem?
Since the names share a common prefix, they will always be grouped in the navigation tree. It does mean you have to review each folder in turn, but if you use a reasonably logical grouping convention for folders, in practice this does not present too much difficulty.