You can reuse a section on another page but it has to have the same information, if you want the same section with the ability to have different content you have to duplicate it. Also each section add's to the JSON file making the admin load slower. We had to move away from Shopify sections because our homepage JSON was too big and kept crashing Chrome when it loaded in the admin. If you are going to use Shopify sections don't use too many on a single page. We went back to a page builder after fighting with sections for 8 months.