So, it appears that the winner of the second semi-final has won 6 of the subsequent 10 finals of the last decade. It's only the last three years that reversed this.
If this is indeed the case, then I don't see the argument for a rest day.
What has happened this year is a perfect storm: the first semi was won by a young man with a session to spare so that he had a full day off, while the second semi-final went almost the full distance and was won by an older man who probably ran out of steam the day after.
While being in the first semi IS an advantage for the final in that you have more time to prepare if you win, winning it with a session to spare is where the real benefit emerges. Hard to fault Zhao for obliterating O'Sullivan. With the best will in the world, I'm not sure Williams would have done that had he the chance. A tough break this year for Mark, I think.