Yes, I wasn't too worried about shear loads with it attached to the house
There are 4' panels at most corners -except 1 corner w/garage door
A couple feet of the back garage wall is underground
That wall only has 2 small windows in it
The wall bordering the house is mostly the house foundation
A short wall was built on top of the foundation along the sunroom - 15'
Only 8' of the 36' length sticks out beyond the sunroom
So 2 walls are "secured" in ground
Most of our wind comes down the street from the East - hitting the Northeast of the house, rest of the house is protected by trees/woods
The long side garage wall has a few windows in it...but mostly sheathing
The front with the doors is always the concern
Full sheets of plywood were used at corners & at the middle support
Full sheets will also be used on the interior to complete the shear wall
If it was free-standing I would have been more concerned
I would say 20' is too small. In SoCal, where I used to live, 20x20 was a standard size for 2-car garages, and it's way too small. Getting in and out of cars is a pain, and going in front or back is a pain, too, especially if want some shelves or something on the back wall.
I built a house here in Arkansas and made the garage 24x24 with two 10' wide roll-up doors. It has plenty of room to get around the vehicles and still have other stuff in it.
Of course, if you have a long-bed truck, it'll probably need to be longer.