I'm thinking abt this for a while too. I was thinking to use the number of hours I want to spend on PP + shooting time, multiply it to the number of photos I can PP in an hour (Rough gauge).
But... considered these:
- How would I know how many hours I would need to finish selecting and PP all pictures?
- Even if one could do more photos per hour, it doesn't mean he or she should produce more pictures of client.
- If I deem there are too many or too little qualified good photos.... what happens -_-"" (Although the earlier case is a better problem to have)
Hence I think, just agree a quantity with clients upfront is still the best. Although you still have to worry not being able to produce enough good shots