Ian- As Sonya pointed out, as long as there are available nodes (previously unspiked nodes whether old or new canes), spikes may come out.
I am attaching an example picture of my nobile. See how there are flowers toward the top and the bottom on the previously bloomed cane? You can sort of see all those dead and dry old spikes from last season.
I do not like it when this happens though.
I like it the best when spikes are made along the entire cane from top to the bottom as these are idealy supposed to. well, not all the way down to the bottom but you get the idea.