I think the key element is to do some math to calculate how much benefit you're getting. This event is at its best with the cheapest cantrip possible. If you can open with some sort of +coin/+buy and piledrive Pearl Divers or Pawns, Pathfinding turns them all into Labs with upside; you go from a bunch of 2-cost cards to 5-cost+ cards and start drawing your deck much faster than buying village/terminal engine parts. Of course, the trouble there is that you're not helping your deck much in the meantime. Have a plan: Nomad Camp, Silver, Copper, Copper, Pawn for coin+card gets you to 8 if the card is a Copper. With 4-5 Pawns, you're in business (...maybe. It's shuffle 3: Do you know where your Estates are?)
By contrast, putting this on Lab or Stables is often gilding the lily. You've already spent gobs of turns and coin on premier one-card-engine cards that are probably already drawing your deck or close to it, and pathfinding them can result in you drawing more cards than are in your deck, which is a waste of resources. Spending time and turns to build an engine that draws twice as many cards as there are in your deck is kind of the flip side of the Village Idiot. (The Smithy Idiot? Or is that someone who buys too many terminal draw cards and complains every time there's a collision?)
And let's not forget the object of the game. If you skip your first province buy to do this, how sure are you that the result will be a post-pathfinding double-buy to make up for the loss of tempo to your opponent? Or, failing, that, a deck that buys a province a turn without stalling when your opponent is playing a strategy that is almost certain to stall after a reshuffle?
Yes, +card is amazing, and yes, it's almost always worth it, but at that price point, know when to ignore it.