Here are my tabs, for now...
@Computer
@Office
@Home
@Phone
Wait-For (Sorted by first name (oftentimes initials, and the creation date))
Agenda ABCDE (Sorted by first name or initials)
Agenda FGHIJ
Agenda KLMNO
Agenda PQRSTU
Agenda VWXYZ
Proj-PG (Project list Personal)
Proj-Work (Project list Work)
R/R (Read and Review)
S/M (Someday/Maybe)
@Errands
Various focusing lists (tabs for each major project/area of focus)
Checklists
20K - HOF (Horizons of Focus)
30K - HOF
40K - HOF
50K - HOF
That looks like quite a bunch of tabs, and I've cut it down from originally way more! It works for me, because I focus more completely within each context. I had to do what I did with Agendas because I work with many people (personal and professional).
After several years using the GTD Systematic Approach, I've converted to a paper system (one system for both work and life - that was a big jump for me). One of my several realizations after switching was that writing the Next Action down encourages me to slow down and really process the item. Spending just a little more time gets me to determine the meaning of the item, position it correctly, and possibly either complete or initially tackle with a 2 minute action. I've created more forward progress knowing that I can subtlety reword/re-categorize the Next Actual Action after doing some work on the item. I'm now using Technology for what it's good for -- full-text searching, MindMaps, Databases, etc and cross-reference within my actions and projects lists.
When I can eventually manually Capture and Process at the speed of light (which for me was a liability because my brain knew I hadn't really committed to what I had lamely processed, so it checked out), I'll go back to using a technology system -- until then, paper is my preferred choice.
What's wild is that my Project List isn't as big as it was within the technology system -- that's because I was creating too many new projects from spontaneous ideas after reading an email vs. parking the idea within a Project's Action Support for a related Project.
Another really wild thing is that I realized my brain can actually make links between actions and projects -- for years, I didn't think this was possible. Sure, I may end up with dupe actions across contexts for the same project, but it all works itself out during Weekly Review.
I agree -- it's a personal choice, so do what works for you. The question I ask myself every so often is, "Am I really doing GTD?"