I'm also surprised they already finished it. Without rushing, we're playing for many weeks now, not every evening but then during christmas holidays a lot so maybe that evens out, and are about to go to Aquilo (4th planet, or place to visit idk, out of the 6 new ones)
Uhh roughly 100 hours of play got from nothing to you win screen. Could be rushed, or you could slow down and and get all legendary and spend 500 hours.