A rudder is a tiny piece of a ship, but its manipulation controls the direction of the ship. The person in charge of the rudder is therefore the person in charge of the direction of the ship.
My experience is that, when I am letting go 99%, I'm letting go of all of the ship except the rudder. I am apt to congratulate myself; however, the all-important last 1% is the precisely the element that must be let go off absolutely for me to be brought under God's sway.
Letting go is all or nothing: if I'm asking God's direction in all of the details but have not relinquished overall control of my life, the destination will be the wrong one, even if I approach the destination in a 'spiritual' way.