This seems counter-intuitive, and I don’t see it in the rules–although I may just be overlooking it. I see linked tests as the building blocks for a much harder goal. If anything, the final test should have the highest obstacle–that’s why the PCs need to link tests to achieve success. I have not been setting requirements on the obstacles for the linked tests. Granted, a PC might want to test a skill he is good at to gain a linked die for a skill he’s not so good at–meaning even a lower obstacle in the subsequent test is ‘more difficult’, but I prefer linked tests to simulate building up to doing something hard.
Mel