How to efficiently add a large product range in e-commerce?

My customer currently has a small e-commerce offering but wants to add their full product range - over 1000 products - to their site. They add products to their current inventory 1 at a time and their main complaint is “getting pages to look how they want them to”. They currently use “Shogun” to edit and style pages individually; adding padding and other elements from “Shogun” with a degree of trial and error. The pages are not based on a template or theme.

As a Shopify newbie, I don’t think this approach (making pages individually) will scale when large numbers of products are added. Templating - if that’s a feature available in Shogun might help. What have other users used to address this problem. Any help or advice is much appreciated