I agree with you, but the same can be said, if she isnt able to make it to the barn to remove and put on those blankets to right.
The weather we have here in Calgary is very extreme, far more extreme than what you're describing and our horses adjust just fine. We can have sunny, warm t-shirt weather with the sunshine and go into a sever winter storm, where it's -20 in a matter of a couple hours. It's a pretty standard set of weather conditions we get here. How do you think horses have managed to survive the last few thousand years?
I am not sure what you call t-shirt weather...it has to be well over 70 before I wear a t-shirt, at 55 (today) I am wearing a sweatshirt and a light-weight coat
So, yes, I have to stay on top of the blanketing, but then I go to the barn twice a day every day, because I do all their care myself, it is not included in the board...
My horse was miserable the first year when I let his coat grow in. I had to shave him because he looked like a caterpiller and was all sweaty!! This was in December I shaved him...I hate shaving horses, it is a pain! So he is much happier now, and yes, it is a lot of work, but I do not mind. When I am not in school all day, if it gets warm I go out at lunchtime to change blankets. He has 5 different weight blankets, plus the fly sheet.
So, he stays much cleaner under sheets/blankets too, and that shortens my grooming time. He loves his blankets & even sticks his head thru the opening when I hold it out. It is funny to watch
I have had him for over 9 years now & know him very well! Other people may be fine without blanketing, but my horse loves it.
Maybe horses have survived thousands of years without the special treatment my horse gets, but they didn't all live & they didn't live long!
I want my horse to live to a nice old age. He is NEVER sick, and I only trust certain people to take care of him for me...my dogs wear coats in the winter too, and they are much happier playing outside with their coats on!