20 Year Techniques
When I first started training, I was told that Shomenuchi Kokyunage was the 20 year technique. After my first 10 years of training I began to suspect that all Aikido techniques are "20 year" techniques.
Now that my 20th year of training has long since passed and my 25th year is staring me in the face, I can say with great certainty that the "20 year" aspect is not that it take 20 years to master any technique, but 20 years to accept that you can only improve and that "mastery" is relative. My students are often amazed at the "ease" with which I do things. I, on the other hand, despair that I am still so "rough".
Remember, O'Sensei said something to the effect that it takes at least 10 years to master the basics.
Yours In Aiki,