Does every haiku have to be 5–7–5?

No. It is a common classroom form, while many published haiku use flexible lines.

Why can two counters disagree?

Syllable boundaries depend on pronunciation dictionaries, dialect, and poetic context.

Count each line, inspect pronunciation, and use manual overrides when dictionary-like heuristics miss a poetic reading.

A common classroom haiku pattern has 5 syllables in line one, 7 in line two, and 5 in line three; English pronunciation makes the count approximate.

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