Having 2 terriers I find the two most important commands to
teach them are "Stay" and "Come". Now could I trust them
to Stay put in an open field with a rabbit hopping by their line of
sight... uh no... That would be way too much reliability to expect
from a breed with such an intense chase instinct. So a leash
would be pretty much required in those instances.

But by teaching them to Stay, I can very reliably have them Stay,
Open the door, Walk through it first and then
have them Come through it, when I want them to.

I'm not sure what kind of breed you have, but for me it would be
worth the effort to try and train them to Stay, cuz that putting
the leash on'em everytime you want to open the door would
get real tiresome.

Par...