You can't trade it, If one person has mon-wed, the other person has thurs-sun, how will they ever trade?
The days each has would never change.
The same person would always have mon-wed, and the other person would always have thurs-sun, there are only 7 days in a week, to trade it as you propose, the person who has thurs-sun would have to take mon-wed as well on the following week for the other parent to have thurs-sun and they would also have to take mon-wed to do the swap as you propose.
Which in essence is a week + weekend each.
The reason for the transitions every 2-3 days in the beginning is actually to make it easier on the kids who wouldn't be used to not seeing one of their parents for 7 days.
I agree with the week + weekend after the kids got more used to the separation.
