I have one horse, Cezar. I cannot remember all the brand names. He has:
1 heavy HIB that doesn't fit, I need to get it tailored or something (this brand stopped making blankets so I bought it on impulse because they make absolutely wonderful ones)
1 heavy Turtleneck blanket (blanket brand that fits uphill horses well, looks like this:
http://www.tackroominc.com/images/Frost-Turtle-Horse-Rug%20Black.jpg )
2 Turtleneck sheets, one blue and one black
2 coolers
1 Turtleneck lightweight mesh sheet
1 lightweight mesh sheet
1 half sheet to be used for riding/lunging in cold weather, if that counts.
I don't put anything on unless the temperature is below 48f, as he spent his last winter in a box stall with heated barn/arena/turn-out so his coat was quite short. Next year the blanket temperature will be lower, although I still have to blanket to keep his coat short enough that he can work during the winter and not need a clip. I also have a few blankets from my first horse at home.