I totally agree with this. I grew up in the North Dallas area and was in the homeschooling program at my club (I still went to school, but I didn't start until 10 AM usually, being ahead in high school credits). We would be warmed up by 6:45 and ready to hit until 9:15, where conditioning started with our conditioning coach. I then went to school, and I got another two hours of hitting there from 2:30 to 4:30, and it was good hitting too, as we were the number two ranked school in UIL 5A at the time. Then, I went back my club and trained from 5-7 and then I was done for the day. This went on for around for my entire senior year (and only my senior year as my parents stopped me from playing tennis consistently from grade 10-11, so I was trying to get back so I could play at a good college level) and it was the most tiring but rewarding thing I had done at the time. Everyone in our program usually played two tournaments a month, where we would travel with the entire academy and our high-performance coaches were there. It was such a crazy day-to-day schedule as it was just constant grind. I was pretty unprepared to start as I hadn't trained that rigorously since I had been 14-15 y/o. I didn't play many adults growing up through USTA, but I played a few at some UTR tournaments and didn't think the level was that crazily different but we could hang in there a bit longer. I remember one match where I played a 9 UTR adult, older 20s, and the guy was pretty good but that was it. To play the other hand though, I've played some tournaments as a 20 y/o where I played a junior whose good middle 10 UTR and won but there are some pretty strong junior 9 UTRs in FL would I ended up losing to or having really close matches with.
In terms of the reset, I played a few tournaments as I was in-season for high school tennis in the spring. I really didn't think much of it at the time, I just ended up playing dudes that were not from the general South more than usual in L2s, L3s, L4s, etc. I think I had a slight jump in UTR but nothing outlandish. I think I finished out high school at like a 10.2 UTR or something like that but that was a long time ago. I actually had a higher UTR when I was 15 than I had at 18! Also, since the reset, I've been told there hasn't been as much good juniors playing USTA as a lot are just going straight into UTR tournaments to get some prize money (also blame NIL for that) or they're starting to travel more for ITFs, but I'd take that with a grain of salt.
TLDR: Yes, Texas junior tennis culture is outrageously crazy.