It's not either/or. It's both/and. We would be foolish to reject the wisdom of tradition but we have to make that wisdom our own and that means we must bring a personal approach to it. There is also the important point that in the modern world things have changed. We have crossed a threshold and are now required, yes, required, to find truth within ourselves rather than simply take it from an external source, however august that source might be, however authoritative.
If I had been born in Saudi Arabia 100 years ago I would no doubt have been a fervent Muslim. If I had been born to a Brahmin family in 18th century India I would have been a Hindu of some kind, pledging my spiritual allegiance to Vishnu or Siva. If a Roman Catholic today who lives his life according to the rules of the Church and believes what the Church decrees had been born in Tibet he would almost certainly have been a Buddhist. That should give us pause for thought. This is the same soul born in a different time and place and believing something totally different according to the milieu in which he had grown up. Unless you consider this impossible. But if you do it seems to me you are putting material things before spiritual ones for you are determining the soul by the body and its outer circumstances. Certainly the soul is qualified by these things but it is not formed by them or bound to them.
Personal discernment can be faulty but the fact that it is not perfect in this world is no reason not to strive to develop it or be guided by it. It should have its checks and balances and tradition and authority can help in this regard. They can also give it the impetus it needs to start it off and set it in the right direction. But they are not perfect either. Besides, do you think God wants obedient servants or co-creators who can work with him to expand and glorify creation? Asking the question gives the answer. If he wanted the former he would not have put us in this world which is specifically designed to foster the development of free will.
In a way that is what all this comes down to. Free will is not just a matter of making the right choice. That is just the beginning, necessary but not sufficient. It really has to do with making gods out of men. If that is to happen these men cannot just be followers. They must be captains of their own ships, able to navigate anywhere in the creation they want to go though always, of course, according to the laws of God not their own whims and personal preferences or they will capsize and sink.
One of the arguments against personal discernment is that it can be unreliable. At this stage of our development that is quite true. But two points need to be made. The fastest sprinter had to learn to walk at one time. If he hadn't done that, and probably fallen over on a few occasions, he would never have become a sprinter. We are at an early stage of inner discernment. We will make mistakes but we will learn from them. God will guide us back to the true path if our motivation is right. If it's not right, that is a different story and then we need to get it right.
The second point is this. Do you think tradition is perfect and, even more, complete? It is not. It may be enough for salvation (though it may not nowadays for this is a different world to that of the past and has its own demands) but it is not enough for theosis which requires full personal and spiritual responsibility.
The question then arises what if discernment and authority clash? Which bows to which? I would say you have to use discernment to decide this question which perhaps answers it. But what use is discernment if you reject it when it differs from authority? If it merely confirms authority and tradition it is obviously just conditioned by them and not personal at all. If it is perversely different then it is too personal and not rooted in spiritual awareness as it should be. Generally, discernment will add to and develop tradition and cast it in the light of here and now. Without it tradition and authority become ossified.