The thing that has me confused is that the Nightvault rulebook gives the example of ‘Determined Effort’ only adding +1 dice to the attack made against the first target, not to any others, because they are all separate attack actions. If it was considered to be one attack action then ‘Detrrmined Effort’ would apply to all of the other attacks as well, wouldn’t it?
I looked in the Shadespire rulebook to see what the rules were before Nightvault but I couldn’t find any mention of it. I wonder if they wanted to clarify the rules for Nightvault but forgot about ‘The Harvest Begins’...