The two major ways I've sped up my macro creation are
- Taking advantage of the Insert Action by Name feature, mapped to ⌃⌘A by default:
I don't remember if this was added in KM 7 or 8, but it's such an invaluable addition to my macro creation workflow that I never use the Show Actions list anymore.
- KMFAM
This amazing KM addition by @DanThomas makes it super easy to store and access customized actions and even macro templates, and is a perfect complement to Insert Action by Name when the stock version of an action just won't do for your needs. You can find it here:
MACRO: [KMFAM] Favorite Actions and Macros