I remember using an adjustable spanner on a nut when my foreman walked past.He asked to have a look at the spanner,when I passed it to him he threw it out of the window. I then had a long lecture about how the spanner for a 1/2 BSW is marked 1/2 BSW and that is the tool you use. Metrinch (what a stupid name) are a vague copy of the tools designed to work on deformed nuts and bolts, the fact that they can be used on various nuts and bolts,similar sized but difeerent standards is coincidental. There are a few instances where (once again by coincidence) fittings are within a few thou of one another 3/8 BSW and 5/8 bsw , 18mm and 28mm for example) and the two sockets or spanners are close enough that they are virtually interchangeable. This has however been taken to extremes by some of these so called universal tools,I have seen a socket marked 1/2 AF,13mm,1/4 BSF which diod a pretty useless job of fitting any.
Each to his own,but I heeded my old foremans advice and have owned and used four sets of sockets and spanners, BSW/BSF, AF,BA and to my shame Metric. I've also followed his lead and thrown a few out the window too.
I've sold tens of thousands of tools over the years,each one designed to fit one size of nut and to fit it correctly,I've also sold hundreds designed to fit chrome plated,brass or alloy fittings or ones that are rusted and/or damaged. I've never sold one that was intended to do both.