Thanks for buy and using the 24 week plan.
We are constantly refining the plans as we get feedback. The changes you note were made to maximize the effectiveness.
We like hill sprints as a great strength workout. But felt that the Z3 hill climbs were accomplishing some of the same things plus more ME benefit so made this change. That meant the longer weekend climbs had to change to accommodate the Z3 ME workouts.
Doing back to back long hike/climbs on the weekends is fine. Most people do this.