[nxb]

> What I have found is that the subconscious will resist taking action on something perceived to be important until it's worked out an appropriate approach.

Yup, that's why whenever I get stuck on the high-level design, I'll often start doing some of the small sub-tasks for which I'm highly-confident will be a part of the end-solution, and for which I'm highly confident that I know the interface they'll need, no matter what high-level approach is taken.

That extra domain work on the sub-tasks often feeds back to helping with the high-level planning too.

This, combined with abstract non-functional high-level prototypes will attack the problem from both the top and bottom. Hopefully you eventually complete the task when you meet somewhere in the middle.