I use singular too, but I always wonder to those sticking with plural - what's the convention for words which plural and singular are the same. ie - like 'staf

I use singular too, but I always wonder to those sticking with plural - what's the convention for words which plural and singular are the same. ie - like 'staff' or 'species' or 'aircraft'. Then I can add suffix to those singular ie - 'staffList', 'speciesList' etc