We recommend distributing the weight load as evenly as possible, for both types of shelves. The Atlas Shelf generally has a higher load capacity as it is supported by the floor - we have tested up to 80kgs on each shelf without observing any flex. Floating shelves on the other hand, rely wholly on the wall for support and will have a lower load capacity per shelf. Please let us know the use requirements of your shelf so that we can advise the correct amount of support needed.