"jack of all trades, master of none" has been spoken so many times that it might as well be carved in stone in the halls of capital
even if it were true, i'd bet mastery is not the goal most people actually want to be achieving. that's not to say it's never the goal, but i think if you intend to release multiple works within a medium and have the larger goal of improving that side of your craft and expression, you can't be concerned with individual skill mastery