Brand or Category?

My first manager job was for a John Menzies bookshop. My first act as manager was to change the categories of paperbacks from by publisher (designed to help the staff and suppliers) to by subject (to help the customers). It's not always so easy though. Many customers shop by brand and want to see all Nike products, say, grouped together rather than spread between various categories.
Marks & Spencer are an interesting example of a shop that seems unsure of which they want to do. In my local, you can shop for Autograph or PerUna clothing by brand but find other stock grouped by type. Except that lingerie comes under not Autograph or PerUna but lingerie. It's the same in the food section. Unlike Tesco or Sainsbury who mix their Taste The Difference in with the standard and Value products in the appropriate category, Marks put similar meals under categories in some cases and under 'brands' like 'Pub Grub' (or whatever it's called) in others. Confused? You will be if you shop at Marks.
It's easier with an online shop because you can do both- as we do at Your Life Your Style, where for example you can click on Glass by Jo Downs and Handmade In UK.
A bricks and mortar store must observe its customers' behaviour and ask them their preferred way of shopping.