"The compressor, liquid line filter drier(if its outside), and accumulator will all have refrigerant in them after you recover.. "
Even if the guages show 20 or 30 vacuum?
Its boiling that slow. that your pump will be pulling that low that your gauges will read that. And shortly after you shut the pump off. the refrigerant will boil off enough to produce what ever X pounds of pressure.
I run into it a lot working on heat pumps, or cooling systems that need to run year round.