Well, as far as I know an Si leading person would be interested in health, balance of life, pleasurable sensations. However what about the Si leading types that are fat and live life excessively or the ISFps who are extremely work focused and have risen quite highly in their careers? The health is negligent in one, the balance of life negligent in both, and the pleasurable sensations negligent in the later - perhaps even all three in the latter.
Unfortunately, socionics, the functions, the types are so vague and ill-defined in any practical sense that so often it is the case that we have to rely on 'intuitive' impressions of peoples types. Even going by 'the book' eg wikisocion produces incorrect assessments of peoples types.
Socionics is a pseudo science which might not actually even exist. Perhaps it's just a philosophical approach to people and relationships.
I would like to agree with you and do things without any instinctive approach, but perhaps considering what i've wrote, you could advise me how it is to be avoided? The only way I can see to avoid it is for a person just to create their own understanding or rather - a more correct word - interpretation of socionics, which no matter how well layered it is, is still built upon some form of 'instinct', personal impression etc.
That socionics isn't objectively defined - I simply back this up by demonstrating every type discussion and every discussion about the functions.