After several semesters of casual university tutoring, I can safely say that when I am teaching, I am not writing. Technically, I write every day, so when I say ‘writing’, I mean writing fiction. If I need to write, I generally avoid teaching for a semester. For me, the endless detail of teaching: the tutorial preparation, answering of emails, learning new digital platforms, figuring out how the kids will get looked after and fed while I’m driving home from a far flung campus – these are the opposite of the rhythm required to write. 
In the early stages, I need empty, aimless days, with plenty of time for walks, fidgeting and driving to cafes. Later on, I carve out of life four-day blocks during which ideally I speak to no one, or only briefly, and leave the house to buy lunch and dinner in one go, ready made. I process huge swathes of material, knowing that after this hermit session, I may not get another for a year. They are expensive, in terms of what others are required to do to facilitate them, and this is chastening and motivating.
Currently, I am teaching. I like it. It is generally energising, I learn a lot that always seems helpful in an undefined way and it diverts me from getting depressed about not writing. So, it comforts me by usefully filling the time I might otherwise spend worrying about writing at the same time as ensuring I don’t actually have time to write. 
If something irresistible occurs to me, perhaps I will stare down impoverishment and take a semester off. But it is more than likely I need to take time off up front as an act of faith in order to begin the required cycle of anxiety, boredom, desperation and if I’m lucky the productivity only self-loathing can engender. Oh well, next semester…