The Branches or the Trunk?

I've been writing a little on and off lately, though the sessions are longer which means the volume is about the same (34,000 so far).  I know that I need to nail down the bulk of my story before I move onto (one word or two?) other aspects, at least in earnest.  Thus I find myself yearning for time in my sketchbook, or Piant Shop, or blender; but resisting the urge to prevent distraction.  That discipline would be excellent if I wasn't in turn side-tracked by YouTube and other miscellaneous internet dross.  Sadly this tale does not come with resolution.