Using the numbering system will control the order of images you add to spec or selection items. Single-digit items need to be numbered with a 0 in front, like #01, so that they will display in the proper order on your Specs & Selections page or template.
You can use the numbering in the file names before uploading or within the photo description once added to the item to control the ordering.
As an alternative, when you have a large number of images to share on a given selection item, you can create one PDF file attachment that has all of the images in it. This way you will only have one file to upload. Any time you have a change in products, you won't have to renumber all of the images to re-sort. Just change that one file and upload it again.