I'm fairly certain a lot of people do this. They don't literally take a day off, but just work fewer hours or less hard. And this makes sense, there is a strong incentive to not give away all the productivity gains to your employer.
I'm fairly sure that if a compiler stops working or has a bug, the expectation is that an engineer is capable of handling it in some way. I don't think any stakeholder will have much sympathy for "compiler stopped working, we can't do our jobs now" argument.
these are all surprisingly specific questions that can actually be answered!
1. It's dynamic
2. It's compiled
3. Elixir script is just a file with Elixir code that compiles and runs right away
4. I've been writing Elixir for 7 years and barely know any Erlang. I even submitted bugs to OTP team with reproductions in Elixir, they're chill.
5. Preemptive scheduler, immutable data