While there is no hard-coded upper limit on the number of photos, there is little quality improvement in the model above about 40 photos but computation time does increase with the number of photos. Using more than 50 photos is not recommended as there are some maximum data size limits on the server and your job may be rejected or fail. Start with a smaller set of photos as you can always add more photos later to the photo scene. It's more about getting 20 to 40 good photos in accordance with the shooting guidelines than having an overly large number of photos.
Clicking away is alive in the lab.