I presume you do realize that the route planner is basing upon your current car's SOC, so if you tend to do your trips leaving at say 90% and your car currently is only at 70%, then that will impact how it plans stops. Given you state this is your third Tesla you've be factoring that it, but just wanted to point that out just in case.
I don't know what your prior Model S was for your comparison. I have just gone from a mid2016 MS90D to a new 2023 MS LR, so in theory, my rated range has increased by over 100 rated miles, going from a car rated at 294 miles to one at 405 miles. Honestly, I'm not seeing what appears to be any significant reduction in my highway cruise Wh/mi numbers. So for me, the range benefit comes mainly from about a 10% larger battery capacity.
What I am seeing is a benefit in charging speed. So even though I'm tending to make similar number of supercharger stops, each tends to be for less time, say 20-25 minutes versus 30-40 minutes.
I will say the route planner doesn't tend to suggest stops the way I would tend to plan them myself. I've honestly never figured out it's logic. I'm still the type that runs scenarios via ABRP ahead of time just to get a sense for how I might want to manage stops based upon my preferences for food, coffee, etc.
Not sure whether any of this helps, but my observations as someone that's just gone from an earlier MS to a new MS LR.
Save travels.