When playing through any extended action, I've never had a single one fail, including the ones I set to high requirements, like 15 successes required. None of them have taken more rolls than the size of the dice pool either. Maybe it's just that the pools I have the characters create always end up being at least 5 dice. 5 dice, 5 times for 10 successes really isn't that hard to get, and the pools are usually bigger than that. Am I missing something? how should I make extended actions more challenging?
This is orthogonally related to making a Homemade flamethrower, in which I feel like even asking for 15 successes was super easy.