I've got a shelf to put up and will be using Spur shelving, or rather wickes version of it. Is there any kind of reccomendation for the spacing of the uprights? I'll be using a 60" x 15" beech shelf 28mm thick. I'm thinking four uprights, does that sound about right? I'm not expecting anything too heavy to go on it but will be using at least 2" x 10 screws as that's what I've used in the past and not had anything come adrift.