Problem is, the Backrooms even with the famous exits like 3999, you can still speed run like mad if you have luck. For example. With 3999, you can literally get an elevator from 0, get really lucky, appear in 153 and walk into a blue wall, then 3999 and exit. You can do that in under a day. Even if not, you can dedicate weeks to just repeating that cycle as it is easy to get back to 0 from the elevator destinations and get lucky.
(So, the speed run I'm talking about is [Level 0 -> Level 153 -> Level 3999 -> Frontrooms]. Literally 3 of the safest levels just being sped run like that to freedom. Crazy.