I've been working my machine from the ground up, spending a lot of time on Zone 1 issues for the past month.
Today I moved to the other zones.
This is an important point. Homer Kelley felt strongly that you should always be working on several things (and not on just one thing). The reason is that you may be having a terrific problem with a certain Stroke Component, only to find that when you fixed something else, the 'problem child' was automatically eliminated.
For the same reason -- though he did not specifically say it -- I'm certain he would have endorsed the idea of those 'several things' being diversified across each of the Three Zones:
Zone 1 -- Body
Zone 2 -- Arms
Zone 3 -- Hands
Working in any one Zone to improve Balance or Power or Direction is always advisable. Working simultaneously on selected, complementary Components in each of those areas is even more so.