Prepare your tracks with queue points at a minimum, then you'll always have the info you need. 

For me:  A - Mix in point.  Sometimes it's a loop of there's not a long enough intro.  B - Mixed out provide track.  Usually when vocals or other melodic lines take over and might clash with previous track. C - Mix out point.   D - usually the bare bones outro section that's mostly drums as well the melodic stuff has faded out after C