I didn't assume anything. I have a friend who played on the golf team at TAMU, and he still has connections with people in the athletic department. He and I have been talking about the ND/TAMU game for the better part of the last year. A couple of months ago, long before you started this thread, I asked him whether the football team practices outdoors during the summer. He laughed and said that doesn't happen anymore, at least not when temperatures are in the 90s/100s. They may hold walk throughs outdoors, or even practice outdoors if the temps fall into the 80s (rare in the Texas summers), but they simply don't hold vigorous practices anymore outside in the heat. They have a state-of-the-art indoor practice facility they opened a few years back, and that is where they practice when temps are in the high 90s/low 100s.
He could be BSing me, but I don't think so. He's a straight shooter. Or he could be misinformed, but I don't think so. He once told me he has a few good friends who played on the football team, so I believe what he told me is accurate.
And that makes perfect sense, though you apparently think otherwise.
I think you once said you played competitive golf. So have I. When you were preparing for a tournament where rain was forecast, did you go out and practice in the rain? Of course not. You got your practice in while the weather was good, and but then you made sure you were prepared for rainy weather: rain jacket and pants, hats, extra gloves, lots of towels, and an umbrella.
As for starting practice at 7:30 p.m., I guess you haven't been to Texas in the summer. It can be in the mid-90s even at 7:30.
Aside from that, it wouldn't surprise me if the NCAA has rules on how late practices can go, but I am not an expert on the rules. I do recall that the NCAA banned two-a-day practices a few years ago, so maybe they have limits on how late practices can be held.