I also learned a lot from GTD like getting things out of my brain, next actions, and zero inbox. Te challenge I found in GTD is exactly what you're pointing out - theres so many projects that it's hard to prioritize and sid you do your next actions based on context it doesn't ensure you're working on the most important things. But I still think some people with certain types of jobs can make GTD work, especially if you have a less creative job and just need to get a ton of tasks done... and you like to work that way.