I'd question whether or not the "10 work-hours" required can be conducted concurrently (by say using 10 engineers - problem resolved in 1hr) or that this would involve disabling the aircraft from flying operations for 10 hours - a small fortune (loss) for airlines, especially the few operating this new Boeing...?!
Neither.
10 engineers falling over each other all attempting to inspect the same engine fuel feed manifold coupling would be daft.
But equally, occupying one engineer for 10 hours, thereby tying up the aircraft for the same length of time, would be stupid - at the very least you could halve the required downtime by using two engineers and inspecting both engines at the same time.