That was sloppy wording, I admit; the martial art of Aikido is effective. I endeavour to make my Aikido effective too.
As to knowing, certain things are obviously such, that continually allowing them in the training invalidates the whole thing, these are exposing yourself to counters, depending on the uke to hold on, etc... . There is more to be said on this but first, will you provide us with the self-correcting procedures you use in your training? I assume you have something to this effect since you stated that Aikido is self correcting.
I've been trained to be aware of openings to counters, and I have trained myself to be aware to what extent my uke is choosing to take ukemi or going along with what I want them to do; the thing with uke holding on is a great example, I really hate that and I strive to minimize that. I don't think this is rocket science at all. You just have to be honest with yourself about who is responsible for the ukemi, and learn how to feel what is going on.