"Usually when you are asked to continue a pattern the assumption is that you are supposed to choose the simplest way. But sometimes it is difficult to decide what the testers think the simplest way is. Can you replace the question mark with a number in the following sequence: 31, ?, 31, 30, 31, 30, 31, … You might say that the answer is 30 as the numbers alternate; or, you might say that the answer is 28 as these are the days of the month."
This isn't to say that Occam's Razor isn't helpful -- it often is, if for no other reason than the fact that model/theory with fewer "moving parts" is simply easier to work with than another with more (and a similar level of explanatory power). Just that simplicity sometimes can't help or that it can be a value judgment.