I recall you talking about the number of steering wheel turns, lock-to-lock. I think my boat is about 4 turns lock-to-lock. I also have a 'rudder' indicator on my VesselView display, so I can see the steering angle at any moment while docking. It becomes inactive while using the joystick, since the outdrives steer independently while using the joystick.
Do you have VesselView with the Merc's ? . . . also wondering if there are some adjustments to the steering sensitivity? 8 turns sounds way to many.
I do like my joystick control for anchoring and docking. The most useful movement is the port/starboard 'crabbing', so I can slide into and out of tight docking spaces.