John Thorp used-to call lightening holes 'weakening holes'... they required significant analysis and testing to ensure that the material removed and the edge stiffening were balanced to ensure that the remaining strength/stiffness of the web was still adequate to carry ultimate loads for the desired life.
For small GA aircraft he was NOT a fan... effort to design/analyze/test lightened [weakened] structure had to be worth the effort. Mass production tooling and high production rates often made the trade-off 'worth-it'... but not onsey-twoseys.
On this subject...
"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away." Antoine de Saint Exupéry
"Simplicate and Add Lightness.” --Ed Heinemann
"Simplicity is not a simple thing.” –Charlie Chaplin
"‘Elegant simplicity’ is never ‘simple’ to attain.” –me
Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov