Out of the box all XF prune settings have values that causes data loss. If the administrator does not change these settings then the amount of data loss can be very significant. Especially when it concerns post edit history. IMO the prune settings should be 0 by default, because the admin can always change the settings to prune data. But once pruned its easy to not notice until its too late. Especially since the installation instruction do not mention that these settings need to be changed to avoid data loss.