A lot of commercial software such as Windows and Photoshop do this, and it must have been approved by legal. So I suppose this is currently considered the best way to do it.

A range like 2002-2020 conveys two ideas: that the work has been around for a while, and that it is still maintained. Both are important for corporate folks who want an assurance of stability.

I always laugh at the copyright dates on this [1] Australian government website. It claims 2003-2020 but I'm pretty sure it hasn't changed since 2003.

[1] https://www.edge.asic.gov.au/004/compportal/get/ServicesLogi...

Not to be pedantic, but wouldn't changing the year to 2020 itself count as a copyrightable change?

single words / short phrases aren't copyrightable so probably not

The whole work with the change would still be under copyright