I need to be highly engaged in a single thing or i get out of it in no time. So PDF questions i had chucked only in two days. But the 202-450 practice questions had the capacity of keeping me engaged for hours together at a stretch. So after attempting the questions, i had the option of seeing my result and then after a couple of attempts, i could go through the result history and also see the correct answers. I could chat with online community members or simply re-attempt a mock to see how i fare in it again. So i had a set of strengths and weaknesses which helped me get out of the rut.