Brent;73833 said:"You Ain't Gonna Need It" [YAGNI] is a great concept for software development--I'm well aware of it, and use it myself in software development--but I humbly submit that it's not appropriate for personal work management, at least not in the same way that it's meant in the programming world.
Perhaps a more appropriate mantra from the software development community is "Do The Simplest Thing That Could Possibly Work" (DTSTTCPW). It's important not to overthink one's system and the contexts.
To apply DTSTTCPW to GTD contexts, start with DA's "vanilla" list of contexts and work with them for a while. If you find they are lacking in some way for you, create additional contexts only as needed. As a Palm user, I have to be very stingy with my contexts; I can only have 15 categories in my system.
For example, I had issues with my @Home list in the past. I didn't like having to locate actions that required my home computer among housekeeping actions, plus I had a pretty bloated list. So I came up with @Home-Computer and tried it for a while. It worked fine and reduced my resistance to the @Home list, so I kept it. I haven't created any other custom contexts.