Yes, we recommend using Universal Protector or Ultra Repel throughout the year.
While the reasoning behind protecting shoes in winter is obvious (more rainfall, and muddier ground), we think that summer can be just as harsh on your footwear. It's worth remembering that a lot of summer footwear features lighter colours and materials - which are more prone to staining - and that the weather isn't guaranteed to stay dry! There are also barbecues, garden parties, and other summer events that could lead to spills and stains. In these situations, we believe that having a fully proofed pair of shoes is invalable.