I was wondering if it was possible to upload folders of pictures or groups at a time because clicking five buttons to upload one picture can get extremely tedious at times, especially participating in the GT6 duel of the week.
Yes, depending on your device type and web browser. On PCs with most modern web browsers, just click and drag your cursor to highlight multiple files, or highlight multiple files on your PC and drag them over post editor, and they'll be uploaded together.
If you're using a smartphone, though, most mobile web browsers don't support this functionality.