I mean, it IS my job.
The comics where I have everything planed out start to finish never get finished and always end up permanently on hiatus.
The comics where I do the "write as I go along" do even worse and never get far and are dead.
The comics where everything is planned out but the dialog and events leading to each other isn't completely finished yet and allows me to work on writing work alongside drawing have been thriving when it comes to creation and both readership. It's just what works best for me. Though do note that my writing is still several chapters ahead (over a years worth of drawing) and all the story-boarding and writing gets done long before I get around to drawing it. Think of it more as writing in arcs or clusters of chapters that could be a book. Those will be completely finished and mapped out before I draw it, just not all the way to the far off last chapter that I don't get to draw for 15+ years.
Everyone works differently, you just have to find out what works best for you, and this can often be more flexible when you're a one man team.