Hollywood, but not the one where they have the Oscars!
I ALWAYS pull the tail through, and almost everyone else I have ever worked around does not ( and looks at me like I have three heads when I ask them to do it). One good gust of wind and you have a sideways blanket.
"You can't really debate with someone who has a prescient invisible friend"
Is everyone talking about the same strap? The Rhino Wug that I have has two straps: one that connects between the edges of the sides of the blanket, close to the hocks (that would be the one that I would call the "poop strap), and a small, elasticized band on the inside of the tail flap that I usually tuck the horse's trail through.
"The formula 'Two and two make five' is not without its attractions." --Dostoevsky
I put a small snap on the side of the horse where the blanket buckles and connect it that way. No fussing with the tail. The strap goes under the tail to stabilize the blanket, as already mentioned. If you don't do that, the blanket can flip up over the back on windy days.
I agree that the strap should be under the tail, but the horse will take care of that if you don't do it. I replace the strap with baling twine so it doesn't matter it if gets dirty, and with mares means less to splatter onto their hind legs.
And with my Amigo Mio rainsheets, I had to make that strap longer for my horses with the BIG rump. Strap did not extend far enough that blanket wasn't rubbing his hips. I added some length, 15"? or so with another piece of strapping and strap was just right. Rainsheet was on nicely, no pulling fabric by the strap all the time, stayed in place on the horses in the wind.
I don't find the strap poopy or wet very often, so isn't much of an issue for me with the covered horse, even mares.
Strap has to go under the tail to prevent the wind from blowing the back of the blanket up. If the tail flap has an elastic band in it I sometimes bother to pull the tail through, sometimes not
Small gripe, Horseware: Don't make tail straps that can't be undone! I bought a couple of Amigo T/O sheets last year and didn't realize that the tails straps were fixed. I prefer to undo the hardware at the back of the blanket and the surcingles and lift the closed-front blanket off over the horse's head. If you want to do that with a fixed fillet string you have to wrestle the gross poop-covered strap over their tail and drag it across the top of the blanket, or undo the front of the blanket and slide the blanket off the back of the horse. The sheets were on sale for $100 which is pretty cheap for a decent T/O, but they couldn't spring the 50 cents for a snap?
As Peter, Paul, and Mary say, a dragon lives forever.