And how do you experience whether your technique is "good" or "works"? Can check your technique really only in randori?
Basically randori is our only benchmark in Aikido. Actually also randori is far from being immune by ukes who still accommodate your technique, however it seems the best we can have as far as testing our techiniques in a more realistic setting is concerned.
Personally, I test all the techniques out of the dojo in a gym with a couple of friends who either don't know what i am going to attempt, or once they know they don't give a damn and keep either behaving normally in the striggle or also opposing vigorous resistance.
This immediately limited the scope of my techniques to a few basic ones plus a couple of customized versions that I would not do in a dojo but that introduce some efficacy against a determined opponent.
About 80% of the techniques I made in a dojo and that seemed to work there, I found out they do simply nothing against an opponent that won't do a thing to help you.
Of course, this also depends on the fact my aikido sucks. No problem admitting it. But it depends also on the fact some aikido techniques have been totally spoilt and wasted by years of malpractice against ukes that do their best to fall as soon as you lift a finger. We too often train treading too fictional a set.
The craziest thing of all is that one of the techniques that you can better place against a realistic opponent is the one I would have judged less fit: nikkyo. If you struggle your way to a wrist, nikkyo just seems the most spontaneous torsion to try.
In my very modest experience:
Major techniques that work:
arm locks of my invention derived from aikido
Ikkyo can work if you quit doing it placing a hand on uke's elbow: place your chest or your forearm on it
kotegaeshi can do wonders, but in my experience it's not easy to "persuade" an uke who doesn't help you to put his palm upward
Major techiniques that never work
atemi: works on "normal" guys, while guys with a boxing background, predictably, are not impressed by it in the least...
Still attempting to understand whether shiho nage could work - mine still sucks so I can't really judge yet about it.