The answer to the question above is (much like the answer to the light
bulb joke), "As many as you choose for the job (joke) at hand."
Today, you can create 360-degree panoramas with only one shot, or with
many thousands (or any number in between). The choices come down to
what you're willing to accept (or settle for), and what your
equipment, budget, and time constraints are.
In photography, everything is a tradeoff.
Higher ISOs mean more noise. Smaller apertures mean greater depth of
field, but require more light or longer exposures. Higher speed and
higher precision usually means more money. Greater resolution usually
involves more shots, greater equipment expense, more post production,
etc. The list goes on and on.
Our job as photographers is to choose the best tools for the job at
hand, or to best utilize the tools we have available for that job.
There is no single correct answer, nor one best solution. That's why
photography -- and certainly VR photography -- is considered a
creative endeavor. Yes, it requires a certain amount of technical
knowledge and skill, as well, but the bottom line is how creative one
needs to be to achieve the desired results within the limitations of
And that's part of what makes it so fun...
Author, Virtual Reality Photography
P.S. How many photographers does it take to screw in a light bulb?
Answer: Ten. One to do the job, three to say they could have done it
better, and six to say they could have done it better AND cheaper.
Answer #2: Only two, but they have to be r-e-a-l-l-y small in order
to both fit in there.