The selection sheets in CoConstruct have categories, which then contain your individual selection items. Especially when you have lots of selections on a project, categories give you and your clients an easy way to tackle related items without getting overwhelmed with what can be a VERY long list of selections.
But how many categories do you need? How many is too many?
It's all driven by the number of selection items that you have.
Ideally, you would have from 2 to 8 selection items per category. If you have only 1 item, it probably doesn't need a whole category to itself. Instead, group it with something else.
When you get more than 8 items in a category, you run the risk of overwhelming the client.
But, of course, there are always exceptions. For example, if you decide to itemize the plumbing fixtures by location, you may end up with 18 plumbing selections for sinks, toilets and tubs. But whenever possible, look for ways to keep it within the 2-8 selections per category. Your clients will thank you!