We use a spring line all the time in tight quarters. It works wonders for making the boat go where you want it to. Of course you're tied to the dock and it's useless for trying med moorings and the like. We use a spring line quite often when pulling the stern into a fuel dock when there's current against us. Or, for rotating the boat out of a slip to point to the channel. Doesn't work well if there's a lot of wind as you can get the boat pointing the right direction and the moment you release the line the wind catches the bow and you're in serious trouble.

The best way if you're in an area with boats all around in close quarters is the tender. We use it as a bow thruster or stern thruster.

I watched a guy going backward down a finger standing behind the wheel. He went down the finger and just backed up into his slip. I couldn't help myself. I flipped him off. (in a neighborly way)