I think in many different spaces, as you begin, you try to copy others who seem successful. As you copy you realize what works and what doesn't work for you and you come to the final conclusion of - do what works for you. I think this is good advice, however, I think we can go a little deeper.
I think we have to say not only do what works for you, but do what fits with you. What fits with the way you think and with your lifestyle.
I have 2 personal examples in totally different spaces. The first one has to do with bodybuilding. The second has to do with productivity apps.
I compete in natural bodybuilding and during contest prep, cardio is a necessary evil. A lot of pro-naturals and guys that have been doing it awhile recommend HIIT cardio - high intensity, interval training - like sprinting, rather than walking. I do this on occasion, but I don't do it every day. Because of personal choices, a lot of my training happens before most people are out of bed - I get up at 4am. I can't sprint at 100% at 4am and do that day in and day out for several weeks. But I can get up and walk my dog at a fast pace, which is what I do. I also have been going on walks with my family in evenings. These aren't HIIT training sessions, even though HIIT would no doubt work for me; I would rather do cardio that fits my lifestyle.
Productivity apps are all over the place - and just about any of them will work for you. But as you try to force someone else's version of GTD into someone else's app you're going to realize that something just don't fit. It doesn't fit your workflow or your thought process. Don't be afraid to not use GTD. Don't be afraid to use GTD in ways that not only work for you, but that fit you. I've found a new love for Springpad and although it's not perfect, I've realized that if I just use it how I want to use it - and not try to make it do something it's not, it's a really awesome app. Although GTD and Evernote would work for me, if rather do what fits how I think just a little better.
Do what works for you, and beyond that, do what fits you - your lifestyle and your thought process.