Keep in mind, Jannik hasn't won a tournament outside of the slams this year. I think he absolutely needs to win some of these tournaments, to rack up the title numbers, to validate his multi-slam year. Roger and Novak, even in years when they didn't win more than one slam, racked up 6 or 7 titles and 60-70 match wins in a season in much tougher competition than with Jannik has right now. I know Jannik was suspended for a quarter of the year, but as of now, his prorated win totals don't match up. If he could finish with 50 match wins and 4-5 titles, it will make his 2025 season look that much better.
But I think the ATP Finals should be 2 weeks after the US Open. Playing these fall tournaments in between takes away some of the excitement of the ATP Finals. Those tournaments can be played in November as a longer ramp up to the Australian Open.