Jumping from bright sunlight into dark shadows presents a significant challenge for the horse. Riders often overlook that a jump is into darkness, especially if it is cloudy when walking the course. Unaware, they may find an otherwise innocuous looking jump will ride much harder than it looks!
"If a horse won't stretch at the beginning of session, work on a contact sooner then stretch when he is ready." ~ Carl Hester
Too much inside rein is a common cause of horses missing their lead changes behind.
When the rider uses too much hand, the horse's hind legs have no place to go, so they cannot stride normally.
If you ride a nicely flowing forward free walk on loose reins long enough, horses very often begin to seek the contact on their own.