Most people are aware of the 5-7-5 rule, that the first line of a haiku must have five syllables, the second line seven, and the third line five, but actually, most serious haiku being written in English today—even translations of classical 5-7-5 Japanese haiku—don’t follow any syllabic patterns at all.
This is because Japanese words tend to have more syllables than English words, so fewer of them can be fit into a line of five or seven total syllables. Furthermore, Japanese syllables are simpler and lighter than English syllables (to the point that they are sometimes barely even pronounced in speech), so there not only fewer words in Japanese haiku, but they are also spoken more fleetingly. All this causes English language haiku in 5-7-5 to sound wordy and heavy.
I write haiku to various patterns: some in 5-7-5 and many more with no pattern at all, but my favorite form is 3-5-3. It retains the fun of writing to a rule, but it’s more challenging and results in haiku that sound more like classical Japanese haiku.