Of coarse it would be hard playing 3 compeditive games for up to 3 weeks, I guess the guys in the B3 already do that though, and everyone would be in the same boat.
Having the second games only day after the first games will be a disadvantage to those who for some reason can't login between those matches nor have enough time to think about their set-up for the second game. Many managers would most likely want to change at least their attitude if unexpectedly won or lost the first game of the series.
Oh well, shit happens. I've lost a playoff game after going 20-2 because I was on holidays but that doesn't mean that I think we should get up a system that works around everyone players life.
Having more time to make those line-ups will make the system work better for everyone.
Of course we can argue if 72 hours is too long or too little time to put those orders in for an average users. Or if 24 hours is too long or too little.