For the Listener: These are different from the other recordings in that each piece is short and read by many different readers. These projects offer the LIbriVox "choice of voice" with numerous readers reading the same poem, who offer very different and interesting interpretations at times. If you have a favorite poem that you can't get enough of, these may help.
For the Reader: The Weekly / Fortnightly Poetry Readings seem to appeal to the both new and regular readers. Since they are shorter everything happens a bit faster than regular projects: project completion, entry into Librivox catalog, and feedback.