I do if I want a real quality finish, I do not if I am in a rush. The OP looked inexperienced so I offered what I thought was good advice for a quality job.
Now how long to take a door off, let us say 2 minutes off 3 minutes back on, nice warm well ventilated workshop to work in, no masking up needed, no fumes in the house, no dust in the house, seems a no brainer to me.
No I do not paint for a living have done in the past though but they were cars and need a lot higher standard of preparation and application to reach a desired finish.