Some people are a different level of productive, and game development sure was different back in the day:

> During his (Sandy Petersen) interview, John Romero (of id Software) introduced him to DoomEd and simply asked him to build a level. Romero was ultimately happy with the results, so Petersen was brought on to production for Doom. The level from Petersen's interview eventually became "E2M6". He was a fast level designer and produced all maps for the third episode of Doom, Inferno. Petersen designed 17 levels for Doom II, a little over half of the 32 total.