Luck pillars are ten-year stretches derived from the month pillar — the chart is the car, pillars are the road; a good car on a bad road crawls, a humble car on a highway travels far.
The pillar's stem sets the first five years' keynote, the branch the latter five (schools differ on weighting). Judging a pillar comes down to one sentence: do these ten years aid the Useful God, or the Unfavourable? What the chart holds awaits triggering — the pillar is that switch.