Find The Keystone
Test each part by taking it out, at least in rehearsal; stop at the one whose removal brings the rest down.
Formerly Keystone
Sea otters gone, urchins boom, the kelp forest collapses.
Seen in Leslie Scott, Jenga, 1983
Try it on your work
Remove parts of the thing one at a time, replacing each before removing the next, and note which single absence changed the whole rather than the part. That's the keystone; you may only mark it, not protect it yet.
Ask three people what the project couldn't survive losing. If two agree, mark that element. If all three differ, the project has no shared centre, which is the bigger finding.
For each element of your plan, ask: if this failed, what else stands? Stop when one element's failure fells more than half the rest. Budget attention proportionally from now on; most plans do the opposite.
How it has been used
Find the piece everything else depends on: the arch's centre stone, the species the ecosystem turns on, the sentence the essay would die without. The move forces the test by removal, at least in rehearsal: a keystone you haven't dared to lift is a guess.
Where it leads
Grouped under Help me name what matters