You are correct David regarding categories in that IF you need or want one, feel free to create it...with the exception of existing projects and accepted/approved formats for categories. The best practice is to post either here on G2G, if in doubt, or to contact the categorization project leaders directly for advice/guidance so that a category and related sub-categories are set to a standard so that one can "blindly" (based on an accepted and established standard) can add a category to a profile. As a creator of many of these accepted standards (ie: Cemeteries for instance), the importance of establishing these are immeasurable so that there is a template of sorts that others can follow.
Categories are an evolving and ever increasing arena for members to make use of, and as they develop it is always important to collaborate with members to insure that they are usable for everyone because of a "standard". So Eugene, as a former Leader, and also the initiator of many projects is well versed in the procedure and also the mantra of "when in doubt" ask! That way is the correct way so that standards are developed that are user friendly to the many members that make use of this great website!
Thank you for your consideration.