LostSoul
Adventurer
No, I don't think this works for me. It's important that the DM doesn't muck around with the PC's odds of success based on their judgement of whether a scene is "cinematic" enough or narratively satisfying. There needs to be consistency in how and where they call for checks to allow the players to make strategic decisions about how they go about sneaking into the castle, or whatever. And they need to be able to fail (sometimes in deprotagonizing, anti-climactic ways) in order to make their plans matter, and not just be fluff on top of a railroad structure.
Two points here:
1. Making a call about "whether a scene is "cinematic" enough or narratively satisfying" isn't tied to Let it Ride. In Burning Wheel that call gets made when the GM describes where the players are and what's going on, i.e. scene framing. (And that call is based on the PC's Beliefs, not if the scene is cinematic or narratively satisfying.) The rule that covers when a test should be called for is under "Vincent's Admonition", I think - roll the dice or say yes.
2. You can apply "Let it Ride" while DMing in the referee style: unless the conditions change, the roll stands. There's a judgement call to make - have the conditions changed enough to allow another try? - but it's not of the sort you state above. This is how Let it Ride works in BW.