> I would cite knowledge of a particular software as a rapidly expiring skill. You can learn a particular software and become an absolute productive genius in i

> I would cite knowledge of a particular software as a rapidly expiring skill. You can learn a particular software and become an absolute productive genius in it, but let a couple years pass without touching it and you'll return to find the software has changed, and your relentless speed and muscle memory is constantly crashing into the changes. Depends on the software. In modern IT-oriented software, or webdev which is basically the same thing, where we have made a sport of rewriting things for the sake of rewriting them, yeah that's totally true. But Someone with 1990s Excel wizardry will still be an Excel wizard today. I'm sure the same is true of a lot of professional software out there where "professional" != "IT".