The Navy taught me this style. I personally would never rely upon solder as a wire repair medium. It's just not sturdy enough to hold a wire repair together (in my opinion).
I made up a short tutorial on how to do wire repair (the Navy way). I saw someone had posted photos of repairing wires with solder and electrical tape, and I became concerned. This repair type is extremely durable, is easy and works great. Plus you don't require power to run a soldering iron. I'm sure most of you already do it this way, but obviously there are some that do not, ......and they should.
Notice the last photo: I made another crimp to show how both ends are crimped independently. I cut back the insulation too far on that one. You don't want conductor showing on the outside of the crimp.
THIS IS VERY IMPORTANT: Make sure no conductor is showing on the outsides of the crimp. Butting the insulation up against the barrel will greatly enhance rigidity, thus increasing the life of the repair. Having conductor exposed on the outsides of the crimp makes the repair very flexible which introduces a "weak link" in the circuit.
One more tip: if you want to use this style of heat-shrink, remember that one end is wider than the other, so put the heat-shrink on the wire before doing the repair, and ensure the wider end is facing the repair so that you can slide it over the splice/crimp. Otherwise you'll have to cut the repair and do it all over again.
I figure the photos can speak for themselves.
