I went for roughly 40 or 50 years without using a torque wrench for most things but I like tools and now have 2 or 3 bike-oriented torque wrenches. It surprises me sometimes how little torque is recommended for some fasteners when I use a torque wrench. And I'm more comfortable with a torque wrench with relatively high-torque bolts.
I have weights and thermometers and other things certified for work so I know what it costs for them. I've never even priced recalibrating a torque wrench for myself. Except for fairly top-end wrenches it's likely to be cheaper to buy a new wrench, so I tend to trust the old ones to be within tolerances. I do have a lot of experience with nuts, bolts, and with wrenches though, so to some extent I think I'd have an idea of a wrench was too far off. Maybe not between 4 and 6 nm.
Loctite Blue is good stuff. I can't think of a situation where using wouldn't be a good idea.
TT