Whether to satisfy particular constraints when writing a poem is an idea that is very important to poets. Some think that following strict constraints (such as building 14 lines of iambic pentameter to achieve a sonnet) is a process that leads the mind to discovery of new ideas. Others think that constraints unnecessarily inhibit poetic ideas.
Over time, the single-stanza poem called "Haiku" has been held to a variety of different standards. Often the Haiku was expected to have three lines and seventeen syllables -- in a 5-7-5 pattern. But this year as we now (in February) celebrate National Haiku Writing Month, relaxation of the syllable constraint is encouraged -- and the challenge of writing one-Haiku-per-day also is encouraged.
Here, using syllable-counts, is a "no-seven" Haiku (offered on the seventeenth)!
one two three four five
six eight nine ten eleven
twelve, thirteen, fourteen