Well, technically you don't have to. I've been adding canon helpers to fandoms that weren't nominated with any. But, if you nominate them it makes things much faster and easier for me.

In order to make sure that the canon helpers get used in the fandoms that need them I am going to set the minimum to one. I'm still debating if I'll allow the use of any in the canon helpers slot of the requests section, as there are often incidents with people using any when what they want isn't in the tagset. So the easiest way to do things is to just make sure I have at least one canon helper for every fandom, even if in some its just a formality.