We had a photography assignment, which my colleagues had planned out very well, and with lots of advanced notice. Included in the plan, in great detail, were very good examples of the types of photos they needed for their project. Because they had a clear idea of what they wanted, it made the assignment much easier to organize.
It still took weeks to coordinate the photographer and the 20+ subjects for the shoot, including their availability during certain timeslots, organizing certain combinations of people, and their wardrobes.
We then scouted locations and selected the venues and got the required permissions to use those spaces. Once this was done, we did the usual paperwork, permission forms, notifications to security, etc.
On the day of the shoot, we arrived early to set up the different venues, including tables, chairs, props, lighting and test shots.
The photographer did a fantastic job, and processed the images very quickly. Once completed, the project was met with great enthusiasm and gratitude. It was exactly what they were looking for, even more than they were looking for.
The success may have backfired, however. People started noticing the great photos and wanted to use them for other projects. The photos are now being used in ways other than their original intention, and in different contexts. These photos had a very specific purpose and goal when they were originally taken.
If you look through existing photo resources and do not see a photo that works for your project, perhaps it is time to plan a new photoshoot. You can build upon the foundation of the existing photos. You could gather your favorites up as examples, which is always a good idea. This way, if you need specific types of photos and you have a budget, you have the freedom to organize and plan a shoot customized for your exact specs and needs.