Ending On A Good Note- Training Challenge or Handy Excuse?

My trainer has always stressed ending on a good note with my horse when in lessons. It always made so much sense, when they get it right, stop and that is a positive reinforcement and reward.  But if you are a timid rider like me, then often you use that cliche to stop before you challenge yourself or your horse. I was visiting a client and fellow timid rider who is struggling with a sensitive horse. She had a very scary experience in the arena with a new horse and has been reluctant to push him...