Time and information are scarce and valuable. How much time and information a person will expend in trying to make a decision is determined by benefit versus cost. A person will continue to research as long as the expected benefit exceeds the expected cost of using time and information. Because information is so costly, we can pay others to do it for us. Consumer Reports, Guidebooks, Counselors, Analyst, Travel Agents, etc.
Choice involves comparison of marginal benefit versus marginal cost.
Comparison requires time and information. Theory a simplification of a reality used to predict an event. A theory need not include every detail or relationship. In fact, the more details, the less useful a theory is. The world is so complex, that a theory can be used to explain it in terms we understand.