Especially when using a panorama head, the 3 extra images will have the very same information. There is no extra useful information for Photoscan to reconstruct anything?
It wasn't so much the overlap I was refering to, as the fact that multiple images with lots of overlap = very similar positions. Instead, taking 5 shots from exactly the same position (a camera station) and spreading out the camera rotations (giving you a wider field of view) does provide a benefit for accuracy.
I've attached a schematic drawing that shows what I mean about positions. Photoscan can get more information from a photo when the camera position is different (instead of only the angle being different).
This is the case if you load all of the images separately into Photoscan, but if you 're using camera station groups you
may find the reverse provided you still have an adequate number of camera stations.