Each of the stars above is a separate image inserted into a table of fixed pixel width to create a divider. You could also reuse the stars as navigation buttons by placing them in a vertical table. A similar divider gif using the same graphics and saved in the width of the table dimensions (750 pixels) would be much, much larger in bytes.

Once an image is downloaded to a computer and stored in the browser cache it doesn't need to be downloaded again (as long as it remains in the cache.) You can use it over and over again on a page without adding any more weight or BW drain than what the single image alone uses.

It helps to keep the page design consistent from page to page within a site for the same reason. Reuse the same graphics from page to page, like BGs, buttons and any other common graphics you can use. Once stored in the (temporary) browser cache, images are free to use again without costing any more BW.

These stars are all the same gif. The smaller ones are the large gif resized by changing the height and width parameters in the image source code. In a page builder you can often resize an image proportionately by holding down the shift key and dragging the image handles.

Resizing an image using html is usually not a good way to resize an image. It doesn't save BW because the info in the uploaded pic still has to be transferred no matter what size it displays on a page. It's always best to create an image in the size it will display on the page before you upload. But if you're reusing a full size image on a page or site, you can resize some of its uses without racking up anymore bandwidth.