one line haiku or three?

You have seen several haiku here in one line.
Most are in three lines. I wonder how much of
the practice of three-line haiku involves habit.
True, some poems have natural breaks in this
form. I worry, though, if we allow a practice
to become ingrained, the structure dictates the
content. I know that sometimes I write a one-line
haiku because it reinforces the meanings of the
words:

another argument unfolds the futon

There is a wonderful little book by Hosai Ozaki
titled: Right under the big sky, I don't wear a hat
(Berkeley, CA: Stone Bridge Press, 1993). All of
the poems are in one horizontal line. The translator,
Hiroaki Sato, discusses lineation in this book,
noting that breaking up original one-line poems
into two or three lines "may be not only unjustifiable
but also misleading" (p. 21). I am not sure of the
ultimate "correctness" of this issue. I do know that
where (if at all) a poem breaks (into lines) guides
its reading and, therefore, its interpretation.

Sometimes, I cannot find a "clean" break to
a new line:

early spring
the crossing guard's
smile

So, I think just write it as one line to avoid the
awkwardness of where to put the line break.
Also, since crossing the street is a horizontal
activity, one line evokes that feeling better:

early spring the crossing guard's smile

Incidentally, I struggled a bit on whether to
make it:

early spring the crossing guard smiles

Perhaps there is not much difference between
the two, but it shows the difficulty of writing
haiku even though, as some people tease me,
it's "only a few words."