The root of the problem:
Your average bike shop, sad to say, especially moreso chain shops, do not spend the 20 minutes they are supposed to spend finishing up the wheels that come with your entry and mid-range bikes. They just slap the bike together - a tad on bike true here and there - and out the door you go.
It only takes a few weeks to a few months for cheap spokes to run the fatigue gamut...might take high quality spokes considerably longer...but they tool will fall victim.
Most entry-bike to mid-range bike factory wheels typically show up in the 70-80 kgf range - which is at best "hold together" tension...and even an occasional one will loosen to a limp spaghetti state...
=8-)
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5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life