I use a thin coat of grease on the receiver threads when torquing an AR barrel nut, the correct torque spec for which is from 36 lbs/ft to 80 lbs/ft. I usually torque to around 50 lbs/ft.
I don't use Loctite on scope rings; I use Torx head scope ring screws, and, per Leupold, use a tiny drop of oil before tightening up the screws.
Here is a guy doing it right. You cant properly torque a screw/bolt without lubrication. The torque stretches the screw and put proper tension on the head to keap it from slipping and thus loosening. Without lube your torque settings are incorrect because your torquing against the friction of the threads -vs- the stretch of the screw/bolt.
There are extreme cases for non hardening locktite. IE: the engineer designed the part incorrectly or there simply wasnt room for the proper type/size of screw/bolt. When most people are using loctite I use never seize. If i want to sell a new part I use loctite so the customer cant tale it apart.