ACtaully. . . it doesn't take forever to make these planets! It only takes 30 turns - 3 years!
THREE YEARS.
How old are you? How many people could you house on one of these planets? How many planets could you make in your lifetime, and so how many people could be born in that time? - hmm? hmm?!
I think Sphere Worlds and ring worlds are great fun to build. You need to be organised and put in hard work. When you have, the rewards are great.