Check out the above videos and watch them in pieces, don’t try to watch all in at once. Both IFR oral videos go fairly in-depth, and can similar to what you should expect on your checkride. The average oral length for an instrument rating is 1.5-2hrs, and largely depends on how sure you are of your answers and how much you have to look up during the oral. The better prepared you are, the shorter the exam will be.