Do you read the guarantees on things you buy?
Well here is one on a door at my local Bunnings store.
DIY door installation
If you are going to fit a door don’t rush the job make sure you paint all edges before you install it.
When its an external door I would reccomend at least 3 coats all over if you don’t want it to shrink and expand when the weather changes.
There is little that is more annoying than a door that continually sticks.
With new houses the guy who paints normally comes along after the doors are fitted so its quite common that both the top and bottom edges don’t get painted.
This is just one of the things you need to check before you agree to the final payment.
For more advice on things to check see the PCI Guide