Surely specific aircraft are not actually being parked? I expect that the equivalent reduction in hours (900-1200 per month) would be spread throughout the fleet with every hull doing 4% less work per month.
I had to laugh at the suggestion of using widebodies on domestic. Which aircraft? Parked on which gates? Both are in critically short supply already, and you cannot make a case for flying a new widebody only nine hours a day. And if you pay 5.5 hrs credit for three hours of flying then your pilot supply problem only improves incrementally. And congestion in this country is a political, not technical, problem.