IMHO any of the standard jointing methods for inaccessible terminations would be OK. e.g. Crimp, Solder, Cold resin..
Basically anything that doesn't need a screw and cannot be undone even with a tool.
i.e. It will NOT accidentally come apart and you would have to CUT it off to open the joint again.
Access / cost and common sense says sometimes it is totally impractical to completely replace a run. Whereas if it was just 5m to other side of garage.. then new cable all the time!