"Most Stock Agencies require interested photographers to submit 200 excellent sellable images for consideration. They will also expect photographers to produce work on spec to maintain and expand their files. Some consideration may be given to the photographer's location, and whether having a photographer in that part of the world will contribute to the agency's subject areas." (Rosenstock, 1995)
"Agencies like to sign on photographers who will be serious shooters of stock, and the requirement is not necessarily numbers of images, but quality of images.
"If you submit 20 really high quality images every 2 months, images that the agency wants to keep, you will be doing very well. However, you will need to launch an agency relationship with a solid file of images. As an example, 250 strong images that go into the agency's files. To achieve this number of pictures you will possibly have submitted a total of 1000-2000." (Seed, 1997)