The way I see it, being willing and able to adjust and change technique is a form of self development. Instead of being tied to a specific outcome, when things don't go as we planed, we can simply adjust and go with the flow. It has come in quite handy in real life situations. It does not mean that you have to always change what you planed on doing but it is nice to have the ability.
As far as I can see being attached to doing one technique when the attack obviously would respond better to another one and forcing it is more jujitsu than being willing to change.
But we all have our own take on what we want to get out of our training and how we want to train.
It depends what kind of Jujutsu you're refering to? I've never been taught to force any technique. If a technique doesn't work, you change, you adapt or if its kata you work out where you went wrong, you don't try and compensate with strength or brute force. Jujutsu techniques when performed correctly, even against resistance, should require no strength.