What I am driving at is that any given sequence in a kata can be adapted to a range of different attacks by varying the movements of the kata within certain parameters.
Kata bunkai which matches exactly the movements of the kata isn't wrong, unless you're matching fanciful attacks into it, but usually such bunkai is only a surface application.
Typical examples are the bunkai sections in the shimbun with stylised karate-type attacks where the attacks are done kata-style so that the defender has plenty of time to execute the particular section of the kata in response. They do not provide for a thinking, moving attacker who doesn't stand like a wooden dummy, after their lunge punch in long stance has failed to KO the defender, patiently waiting while the defender steps/turns/repositions to execute the kata sequence.
The trouble is that the keys for unlocking kata were not passed along in most cases.
Obviously the best way of learning would be to find a teacher who knows which is difficult as they would seem to be few and far between although as this knowledge spreads there will doubtless be many pop out of the woodwork who claim to have known all along (hmm that sounds familiar, must have heard it somewhere).
The next best option would be to train somewhere with solid grounding in self-defence techniques - easier to do but have to watch out for self-styled commando types.
Or you could do what many seem to do - that is to pull bunkai out of their rear ends and serve it up to their eager students who are sufficiently awed by the position of the teacher to dare not question...
All my own opinion naturally...

Mick