Custom schema names, I need the behavior warned against in the docs. How do I do it?

The problem I’m having

I’m using dbt-core. I need unprefixed custom schemas in ALL environments not just prod.
Custom Schema Docs say that you shouldn’t remove {{ default_schema}} from the macro because “developers will override eachother’s schemas” what that means is unclear to me but how can I avoid it.

I need that exact behavior no prefix scehams. Our envrioments are all multitenant separated by schemas to mirror production.

So do I have to use generate_schema_name_for_env only works for prod and I can’t find the implementation of it anywhere but I assume removing default schema there would have the same effect?

Any help is appreciated this is pretty much the only thing holding us back from being able to use dbt easily.