I used to do so religiously, but not so these days as I forgot once or twice and from results it seems optional.
Ok, as people are not bothering to update, I won't any more either. I found it only took a few seconds, so not sure what trouble PLANT is having, but it doesn't sound like it is going to be a problem.
One piece of advice. Make sure the address you give the check in agent matches what you tell immigration. That was not a fun experience.