Too much preload is a cause for early failure on wheel bearings, nearly all the greased wheel bearings call for 0.00"-0.02" of end play.
I torque mine to 50ft/lbs and then back off 90, and the back up to where the torque starts to increase and then move as little as necessary to get the castle nut or pin to align.
My truck uses an outer sprinkle nut as well and that adds preload too.
As far as my TT it has about 7K miles on it and I so far have just been adding grease. I plan to inspect the bearings here soon.