In any case, the interview is over at that point even if the talking continues, and the individual has removed himself or herself from consideration for the job. A related error, and perhaps the most damaging of all, is to try to tell the potential employer how to run the business. It could seem like the perfect opening to show that you are not like other job candidates. You have something special to offer and here is your chance to show it, especially if you had experience or observed a situation where a similar problem or situation occurred. However tempted you may be, do not act on it.
Employers know what they want and what they are buying for their companies.
They do not want to be told that they need something else, or should make some changes in their business procedures. The facts are that the employer knows very well how to run the business, and while the person is open to suggestions on how to improve profitability or market share, these are not the appropriate subjects to be discussed by an entry-level job seeker with limited or no real knowledge about the company. After you have been with the company for awhile, long enough to know how the firm conducts its business, there will be ample time to make suggestions for improvements. As in most matters, it is all in the timing. The job interview is not the time to try to demonstrate anything other than knowledge about your own background and capabilities.