To finish the thought on retention knobs, I wouldn't recommend using impact wrenches, but you do need to control the torque when installing them. There are very low priced click-type torque wrenches available (I know they are cheaply made, but his isn't surgery). Buy one for each different knob socket you use. Set each to the right torque and lock it down, tape the handle, use torque marking compound, anything to keep it from being changed. While at it epoxy the socket to the wrench. Single purpose and preset = LEAN.
Why? Even expensive torque wrenches are hard to read so constantly changing the setting for different knobs has potential for error.
The amount of torque is a moving target with different values recommended by different manufacturers. I would lean more to the light side to ensure there is not taper distortion. I have never seen a pull stud back out, but if you are still concerned, add a thread locker like Loctite.
How long does a retention knob last? Why risk it? They are low priced so decide on an interval, lets say one year of use, and change them out. Some clever distributor out there might send out an email reminder to replace it, like an oil change, one year after they sell a retention knob.
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