Personally I share your intuitions about it being more like an infection and that it's a better scavenger for nutrients and it will outcompete GFO and so on.
When did you run the first treatment? I find that cyano generally will die off in a slow process so if it's only been a few days, wait at least a week, maybe even 2, before deciding on a second blast of it. I've been fooled a few times thinking "oh, it didn't get it all" only to discover a week or so later that it really did work 100%, it just took its time getting there. I suppose a really *awful* infestation may require two treatments back to back but ... I've seen pictures of your tank I kind of doubt it was ever that bad unless you're really good at hiding that sort of thing
Anyhow if you did want to do a second treatment, I myself would be inclined to do so after the w/c.