Yeah Dualstroke, you are thinking of the nuts that have a setscrew against the thread. I had one like that on my Raptor. Rusted and seized in, I couldn't loosen off the setscrew or even drill it out (setscrews are hard). I heated the whole nut red hot to try to soften and free the setscrew, and used a reverse drill and impact driver and HSS bit to try to back it off. It did mangle the axle threads so that I had to clean them up and buy a new nut.
The dual nut system works well when done right. A bit of med strength locktite is useful under the outer locknut, (mainly to keep rust from forming in my opinion). It is commonly done, so I always use propane torch heat to help remove the nuts. Just enough to get oil to smoke. It will melt the locktite without damaging the nut or axle.
The nut that Plankz is talking about is split and clamps tight. They come in many styles:
I've used them a lot in industry and as a replacement on my 660 Raptor.
They are an excellent nut in either steel or aluminum.
Markblaster's description is pretty good. Due to the fine thread you have a lot of mechanical advantage on the bearings and spacer sleeve. Too much pressure is not needed and in some cases could damage the spacer sleeve, binding the bearings. Too much pressure on the lockscrews could strip or break both the steel or aluminum nuts.
So, clean the axle threads, spin the nut on, tighten the lockscrews up so all play is gone but the axle nut spins freely by hand. Spin it up against the bearing, then use the tool to tighten the nut up snug, without marking it or bending the rod or damaging the holes. Then tighten the lockscrews up evenly with a standard allen key. No extenders or grunts or sweat needed. You're good.
No locktite is needed with this system, although I tend to use the medium strength stuff around here as a rust preventative because of the salty environment. Locktite only on the lockscrews. Antisieze or rustproofing on the axle threads. Hope this helps.