Vet hosted dinner.
I went to a dinner hosted by a local vet, and the anal gland question was raised. He said that he is all for groomers expressing anals. He even suggests noting what the discharge looks like and going over what is abnormal. He also pointed out that all dogs no matter what the size have the ability to express their glands when they have a bowel movement however that expressing them will not weaken the muscles around the anus that control that. It was really nice that he hosted something like this. I don't start puppies out unless they present with a problem but I always check the area we put our hands on these dogs every 4-8 weeks and it's more likely we'll catch something earlier than an owner particularly in that region. I was luck and found an anal gland tumor on a clients dog that I hadn't noticed the groom before when they took it to the vet it was cancer but they caught it early enough to save the dog.
Gentle pressure is all that's required I just don't feel it hurts to check and express if needed. Blast me if you want.
"I've seen a look in dogs' eyes, a quickly vanishing look of amazed contempt,
and I am convinced that basically dogs think humans are nuts." - John Steinbeck