How do you measure martial ineffectiveness? Can you do so in a dojo?
By sparing, if possible with other style and situational pressure testing. (So as long as we talk about close quarter, and no fire arms, yes it is possible in a dojo)
In any case sparing/pressure testing will always tell you what does not work
As it as been mentioned before, there is a technical, tactical, strategically aspect to any fight be it in earnest or for play as they used to say in Germany.
To make it simple and for this discussion purpose if we define
Technical as covering how you do things
Tactical as how you go about making things and how they chain together
And strategically has how you prepare yourself and the environment, ideally to have a tactical advantage from the bat and what situation you would like to bring the fight into.
For me the trick is not to know what to apply when, it is to know how you create the situation where you can apply a technique and what you can do it that technique is resisted.
Randori --with kokyu throw version of a given technique is fantastic for that.
You do need to have the degree of fitness and body conditioning adapted to what your policy is.
And you do need to spare to underetand what you can expect from your opponent and what you can reasonably achieve/the steps to create a situation where you will get what you want.
Irimi is important but it is just a technical tool, but you just need to know when you to go against tem to let them go by (another thing they used to say in Germany a few hundreds years ago)
All the irimi in the world are useless, if you get leg baited and don't know how to suck it up or how to see it coming.
I hate to use that word because it makes me sound like the natural son of Candelizza rice and Donald Rumsfeld but to be effective you aikido need to be "full spectrum"
Ie sokumen irimi is exactly the same as elbowing or punching/palm strike /tekatana. Someone in the face/throat. The only difference in the strike is range and the only difference in intensity is what we want to achieve.