* FWIW:
* I frequently (well, almost always), use a "Camera Main" and a cluster of "Camera WIPs" (where WIP = work in progress). The main camera is generally locked.
* I have set up a number of empty C3D.jas templates where useful camera templates (front, side, top, axonometry if required) are available for copy and paste. The templates also contain other settings (resolution, background, some standard materials, specific layers I use) which I use habitually / to maintain continuity in a specific project.
* I also save the WIP stages reasonably regularly / manually with the "save as" menu command and a numeric iterative suffix. If - inadvertently - I move my prime camera I can always go to the last .jas and just copy the camera without losing any intermittent work. Unless, of course, I edited the params for the camera itself. In which case I just have to copy&paste the parameters.