A long syllable widens its note's column instead of overflowing into neighbors

Note-to-note spacing in a vocal line must expand locally wherever a lyric syllable is wider than the duration-proportional spacing would otherwise allocate — lyric width is a spacing input, not an afterthought painted on top of fixed note spacing.

Gould; Ross (underlaid words may demand wider spacing than the notes alone require).

This rule needs the notated content and the rendered result together — the score says what should happen, the page says whether it did.