This is especially true of poetry, where length seems to dilute rather than enhance. Poetry seems to benefit from a special intensity, best maintained by not wittering on. Here's what Lao-Tzu had to say:
Spare words: nature's way.
Violent winds do not blow all morning.
Sudden rain cannot pour all day.
What causes these things?
Heaven and Earth.
If Heaven and Earth do not blow and pour for long,
How much less should humans?
The above is a quote from the excellent translation of Tao Te Ching by Stephen Aldiss and Stanley Lombardo, published by Hackett, ISBN 0-87220-232-1