If I have the runes, and want the benefits, much along the lines of what Darielle has said, then I will tend to push a Wonder to the next rune circle point and get that upgrade without needing the KP. My city can get a nice bump this way. As a result, I will end up with a number of Wonders at lvl 6 or lvl 11, etc. Without sufficient rune shards, I will be doing more donation than upgrading so I can get those shards.