a) The requirement of running it forever doesn't make it pointless.
b) 1. Not knowing the outcome doesn't mean it's not worth trying. 2. It's not entirely true - SEO is about getting your phrase as close to the initial position as possible in an ecosystem with many contending players, whereas this is about introducing noise in your personal data.
c) I beg to differ. When the signals change, why shouldn't the profile change?