How to shingle around roof bends and height differences?

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

1. 1
   bending shingles around angles with staples
2. 2
   using custom transition metal or aluminum coil flashing
3. 3
   Folding the flange inward to mold around adjacent caps and applying butyl tape with fasteners
4. 4
   Bending custom Z trim for the valley
5. 5
   Bending custom metal to create a mini wall that sheds onto the lower roof before installing the ridge vent
6. 6
   Installing a waterproof membrane on the low-pitch section and running it up the steeper section beneath the shingles.

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.