Can't remember where I read it but I think it was a couple of City players who said 2 days is even enough for them, they would happily play 3 games a week if they could, but I think it was also fringe players who said it so of course they don't know how it's like to play every game a whole season with just 3 days in between. Then of course you have monsters like Inaki Williams who tonight will play 229 consecutive games for Athletic Bilbao -- never left out, never injured, never suspended. of course, Bilbao doesn't usually play many games in season unlike treble-chasing teams..!
I know Mane and Salah would never give up a single minute even if they played 3 games a week. Those guys are recovery monsters, they stay up til 2 or 3 am after a game just to warm down and cool down and then rest properly. And then they both happen to observe fasting, didn't eat or drink an entire month from dawn to dusk until last week -- and still ran like demons.
Early game today too, strangely, I got caught out as thought it was 7pm or 9pm my time, but starts before 6... so might even miss a bit of first half =(
I would guess that it wouldn't be a problem for a part of the season, not the early in because it would be getting hard to get used to it, or not the very late on the current period, but somewhere in between. Imagine it this way, one game in Tuesday, then another on Thursday and another on Saturday? That wouldn't be impossible to do, it would be quite difficult but not right now because they are already all tired.
I agree that Salah and Mane would be willing to play 3 games a week, they would literally "try" to play 7 games 7 days and they will fail because nobody can but their mind would tell them to at least give it a try. Inaki managed to do it because he played most of those games once a week, that's why, only a few for cups and all.