It's also worthwhile to remember where the team honed their craft, as was also mentioned in this session: The early id team worked for a publisher called Softdisk that provided a game subscription where customers received a new game every month. This was basically a way to iterate on the practice and process of game development in one month cycles. The shareware relase of Doom had four months of development, which sounds crazy short by today's standards, but for them it was unusual to have so much time.
Wikipedia says 1 year: official team development started Nov 1992 and the first episode was released Dec 1993. IMHO this is underplaying it given Carmack started on the engine before that and it evolved from Wolfenstein 3D.
Yep, I remember him adding emphasis while reminiscing the Softdisk era and how forcing themselves to push new stuff on a tight schedule may not have been the right conditions to produce anything of quality but it gave them the right conditions to hone their skills.
What I'm uncertain is, whether this was mentioned in the book "Masters of Doom" or Carmack's interview on Lex Fridman.
There's several talks on Youtube by John Romero where he tells the story of the early id software, e.g. https://www.youtube.com/watch?v=E2MIpi8pIvY