Newbie question about 3.73 locking rear axle on F250 4x2

Just to play I often engage my electronic locking diff after backing out of my garage in the snow if the truck slips trying to pull forward. I don't think it has ever offered enough additional traction to get me going. I need to engage the 4wd. I guess when one rear tire is on better ground than the other it can potentially make the difference but don't expect much.