What do you mean by "mathematical training"? Or by "practically"?
Mathematics is used in different ways by different people; the form of training each should receive will vary and hopefully correspond to how they intend to use the results. However, creating patterns, recognizing patterns, and applying patterns are common themes across many of the forms that are practiced. If you want a general answer that may make sense, that answer would be that such problems should give practice in the creation, recognition, and application of patterns. If you want a general answer that is correct, that answer is that it depends on whether one is going to encounter items in arithmetic progression, or triples of tangents, or expressions in terms of signed sums of x,y, and z. Mathematicians (and other practitioners of mathematics) are making connections between the past and the present all the time, and it is often unclear how today's patterns will be used tomorrow.
Gerhard "Knowing The Future Is Boring" Paseman, 2015.04.14