Theres a lot of work to be done for each image and for good reason. Everything from a title, keywords, description, gallery organising, submitting to groups, customizing product placements, social media plugs if your using them. Each of these processes, if done well, increase your images exposure potential and are critical.
If you are interested in sales of your art, take the time to maximise your chances because every bit counts. Whether you submit 1,5 or 1000 at a time, the process if done correctly will take the same amount of time. I doubt you will do all those background processes as you bulk dropped 1000 images on the site. So take the time.