On Page 126 of the World of Darkness Core rulebook, it defines extended actions, making no reference to exceptional successes.
On page 125 it defines exceptional successes for instant actions.
Throughout many nWoD books there are abilities that are extended actions and have the exceptional success rule.
For years we have been playing and have adopted several different house rulings on it:
- Total Successes>5 (ie automatic on many rolls)
- If Final Roll brings over required target number by 5 then it is exceptional (this means best chance of exceptional, on extended action requiring 30 successes is to first roll 29, then roll 6 more)
- 5 successes on first roll
- 5 successes on last roll
- 5 successes on any roll
But surely it is actually officially defined somewhere. It is a fundamental system mechanic
I known in nWoD-2e it is really clear, but I am only interested in nWoD-1e answers.