I'm a practicing mechanical engineer myself (working for a torque tool manufacturer right now), and have also taught engineering at third level. From an educator's perspective, one of the things that's always useful is to find guides like that one that break down the engineering/scientific principles in an accessible way. You're not the only person who is posting on this thread, and certainly not the only one who will ever read it, so it's a bit self-centered to assume the article was linked for your perusal alone.
There's no difference in practice between torque + angle and "torque + angle to yield" in terms of the instruction to the operator or to a large degree how the fastener feels when you're tightening. VAG service manuals don't draw any distinction between TTY and standard fasteners either in terms of torque spec or instruction to replace or not. It may be the case in service documentation in other brands/fields, but not something I've ever seen in VAG or Porsche specs.
As to engineering practice, I like to look deeper into these things and see where there is leeway to adjust from the specification in the service manual. Service documentation is written for technicians to get the job done repeatably and well, and as such is always a good starting point, and generally I will stick to the manual and advise others to do the same. That said, there are situations where you need to deviate for some reason, maybe lack of resources, or you need to get the job done with what you have to hand because time's tight, and understanding how/when it's ok to deviate from the manual is useful.
In the case of this thread, it's useful to know why some bolts must be replaced, and why others could be reused with care, particularly for someone who comes along later and finds the thread, and maybe at some point in the past they've reused a bolt that should have been replaced, and knowing why helps/encourages them to go back and remedy it.