Read this forum thread and see if it does not shed more light:
In answer to your direct questions:
1)Lots/most folks are topograpahically challenged when it comes to finding steep enough terrain to make these ME workouts their most effective. So, what to do? Stairs in a tall building, Stair Machines, Gym ME workouts as described here: https://www.uphillathlete.com/mountain-climbing-strength-workout-muscular-endurance/
2) Life can easily disrupt any training plan. You can’t be a slave to the plan. You need some flexibility. These ski touring days certainly were good things to have done for your fitness. They probably had a string aerobic training effect coupled with the ME effect as well due to the pack weight.
3) Yes, smart move to drop the ME right before doing 3 bigger ski days. A mini-max session would be a good thing to stick in that day.