I've had 6 bearings put on my car.
The first four (2 on each side) didn't last 10,000 miles. Either they were not regreased, or torqued properly, despite me stressing it to the mechanic.
The last two have been on the car for 25,000 and 15,000 miles respectively. No problems yet, because I've had to watch them like a hawk when installing.
Grease matters, FOR SURE. Torque matters, FOR SURE.
Now if only my tires were quieter...
VK