I don't remember drilling holes in trusses.
It was never allowed.
Joists were a different story.
One carpenter I talked to, said joist manufacturers had guidelines.
It was a simple math thing. Size of hole, number and spacing of holes, width of joist, distance of holes from center or end, span of joist.........etc.
It sounds confusing, but the math is like sizing conductors for pipe fill.
When we rarely had to go through a truss, we told the carpenter the situation, and he either 'boxed' out a section or showed us a better route.
Joists are one story, but I feel one should never, ever, drill a truss!
