Should be ( I think!) 7 main tail feathers per side on both sexes, plus sickles in the adult males. If your birds have multiple feathering, they would have more than 7 feathers per side. They could have more sickles as well. You can count the feathers, but I promise all your birds will have the typical number. The birds with fuller tails have a better horizontal spread, combined with wider feathers.
http://www.feathersite.com/Poultry/CGK/Longtail/ReederLongtailGenetics.html. This link will be useful to help you understand.
http://www.feathersite.com/Poultry/CGK/Longtail/ReederLongtailGenetics.html. This link will be useful to help you understand.