It's obvious that Written in the Stars is good for Norman, but in this review, I'll talk about other seeker investigators.
This ability is very powerful if you discard good skill card which works during investigation: Deduction, Perception, or Eureka!. Currently, most seekers can perform 4 investigation actions for a turn thanks to Eon Chart & Ariadne's Twine. It means that Deduction gives 4-8 additional clues, Perception gives 4-8 cards, and Eureka! gives approx. 4 cards with searching. The problem is that we don't know the top card of deck. There is some supporting card in , but how about taboo-ed Scroll of Secrets (3)? We have 3 chances to check the top of the deck.
Additionally, Amanda is another investigator who considers this card without any supporting cards. Commonly, she contains lots of skill cards which work during investigation: Deduction, Perception, Eureka, Unrelenting, or Leadership. With her investigator ability, she commits 2 cards at each investigations. Additionally, most cards in her deck has or icon, so that even if we play Written in the Star without checking deck, discarded card could support the investigation; of course, little deck tuning may be needed. In my case, very few cards contains no-: Hiking Boots, Death • XIII, Cryptic Research, Pathfinder, Forewarned, Shortcut(0), Mr. "Rook".... Even if those card is discarded, it's not critical for Amanda; it's because deck tempo of Amanda is fast enough to cycle your deck.