Do you need separate winter and summer coolers for your horse?

I have been looking at horse coolers, and I noticed there are light weight ones (cotton, lycra) and more heavy weight ones (fleece, wool) and I was wondering if you need a separate cooler for summer (a light weight one) and a thicker one for winter (fleece) or can you just use one type (fleece) all year round? I live in Canada, so it gets really hot and really cold depending on the season. What do you use? Thanks for your suggestions!