I had an ENT surgeon recommend surgery for my son that used to get recurring ear infections. The surgeon wanted to remove the tonsils and adenoids and put in ear grommets. Sounded drastic for something that would clear in a week. I researched the situation and decided to not proceed. After his recommendation, my son didn't get an ear infection again! I'm glad I researched the situation and didn't proceed with surgery.
Yes disc herniation surgery is statistically no better than no surgery. Someone at work who has disc herniation told me as much. I've heard of other surgery that fits into this category.
I think surgeons spend their time honing their surgical skills and not necessarily continually researching when to perform surgery. At least we all agree that if a tumor is no longer growing (or grows by no more than 3 mm from initial imaging) there is no need for surgery.
Measurement error is still a big concern. It's nice to do your own measurement and get a feel for where the measurement errors are.
With regards to tumor growth, see https://www.anausa.org/smf/index.php?topic=23404.msg979773728#msg979773728
. My conclusion based on the cited studies was "In summary, it appears that the evidence is that about 13% of tumors grow more than 2 mm".