Currently, the default config has a ringworld equivalent to five large planets and a sphereworld equivalent to ten. Yes, the real numbers should be in the thousands. But think... a single planet has a single build queue. It would take centuries of game time to fill one of these worlds with facilities.
You can change the default settings though. I don't know what the limits are, but I bumped ringworlds and sphereworlds up to 5 and 10 'huge' planets instead of 'large' in my custom set. 80 Billion standard for a sphereworld and 250 facilities, going up to 96 Billion and 300 facilities for a race with 'advanced storage techniques'.