It’s hard to write about joinery in plain english and properly translate the concepts that are important to understand. Most folds take several steps of planning and operation, they don’t look pretty during the process so it’s not very photogenic. It is also not so much fun to watch except for someone who is learning how to seam.
This is the biggest issue in America is education: There are so few roofers (even “historic” roofers) who understand how to seam, because the market is making money training people to do sub-par methods with caps, and sealant, and screws.
We don’t even understand fully the impact of what we lose by choosing to continue the “production” roofing methods. Mainly: lost wealth. This goes for the whole exterior of the house. We chose to put our wealth in the pockets of manufacturers: producing cheap windows, plastic and aluminum siding, and veneers. These products might give you a temporary “curb” appeal to the un-educated when they are new, but over time that initial investment will depreciate, and need “remodeling” in a generation or two. This means there’s a secondary market for disposable roofs, siding, and windows that you are locked into every 20-30 years.
The more prudent way to build wealth in a property is to restore the exterior (strip and paint if wood, tuck point with lime putty in brick). The windows can also be restored, and when properly restored with a storm window they function just as well as those plastic replacements which do not last.
Durable methods and materials provide a lasting true value that will not be chipped away at by future needs to repair or remodel.