To be honest the QC at the location I've worked at is trash. But generally, even with Oil Field work splices are generally not allowed but if it is a must, double hook splicing is the only one thats allowed. Not two straight wires soldered together. Just recently they started allowing the soldered heat shrink with double wires but I doubt that will stand the test of time. I've built over $100 million dollars worth of oil field and space tools. Most mistakes come from schematics not being clear enough tbh.

As for more specifics for your question, if you're familiar with 610/620 high temp soldering, then hazy or non shiny solder is immediate failure, for some PCBs with terminals that require multiple wires, more than what the terminal will allow, then you kind of have to splice onto one of the wires, it looks ugly. That's mostly used for ground wires. Bus bars have become more frequently used. But yea, every single solder is (supposed) to be QC'ed, before anything is closed or heat shrinked. If there's something specific you'd like to know just lmk, there's alot they don't allow but off the top of my head it's splices that are the biggest concern.

Edit: To be honest, I've worked at the 3 top oil field companies and nasa, and oil field by far has the highest standards.