File Arrangement

Hello!

How do you arrange your files in your website directory?

I used to have all files in the same directory.
Then I made a seperate folder for each page.
Now I see that sometimes I use the same file, image for example, more than once in seperate pages, and the same file exists in many folders.
I ve seen that some sites have a folder that contains all the images, backgrounds etc and they link from all pages to that image folder. Is that convienient? I m afraid it might take more time to load if the file is in another folder? Or thats not true?