I don't like the notion that "your skills as a writer" simply top out after, let's say, "6 months" of interacting with a platform. Writing is evolution, and evolutionary adaptations don't conform to a schedule. Writing may, however, adapt to its environment, but those adaptations may not have little use-value when plied in a different writing environment, a different platform, let's say. So forget about the professed schedule for your writing's progress and just let it adapt and evolve in its own manner.