Probably not the right moment to bring this up as Xavi had one week for preparation, but there is a big difference between big teams who play literally every 3 days and smaller ones who only have league and some Cup matches. Also to note that there is no training possible during international breaks as most of the squad is travelling the world to compete with their national teams. For them just to return totally exhausted from playing and travelling.
Under these circumstances, big teams don't have much time to actually work with their players. Work=training
Don't think there will be intense training sessions during season when you play all 3 days. Most of the time will be used for regeneration and then you also have to travel to away games which is usually once a week, sometimes even twice. Then you have some promotion games during the off-season, players returning late from vacay because there was a World Cup, Copa America etc.
In conclusion, you have much less time for preparation, trainings compared to smaller teams who don't have all that in that extent.
Take Girona. Most of the season they play once a week. Which means they have 4 to 5 days they can actually work with players and prepare for the game on the weekend. No travels during the week. Just training. Key players will be rested due to that and if Michel wants to he can field the same team every weekend since rotations aren't really necessary because his players get enough rest.
We could argue that a game is a better practice than a training session, but I don't agree with that. What you have written about EPL underlines my point.
Pep recently complained about scheduling and here is his take on that topic. I agree with that and can follow his reasoning. Worth a read:
https://www.cbssports.com/soccer/ne...congestion-good-food-needs-time-to-be-cooked/