On Oct 9, 8:41 am, wrote:
My friend says I can use flat shingles to cover the apex of my roof.
But I see there are special "Hip & Ridge" shingles for this purpose.

Why are they better?

They aren't necessarily, but they are perforated which allows them to
be separated and installed faster. Also, the hip and ridge shingles
are generally laminated in multiple layers, creating a better look
with modern "architectural" shingles. They are pretty expensive.

To get a similar look for less expense, I often "double up"
conventional shingles along the peak, which mimics the look of the hip
& ridge shingles at a lower cost (but more work).

Why are they folded like that?

Unless I'm not understanding your question, the simply answer is that
you can't cover the "apex" of your roof without "folding them". It is
a ridge, and you have to cover it to prevent leaking.

JK

TIA