I've always thought having a doctors note proved you were really very unwell. I've fortunately never had cause to ask for one until fairly recently.
However during Covid I had a bereavement and wasn't coping very well. In the end I admitted defeat and was eventually signed off for more than 4 months. I never saw a doctor, just spoke to the receptionist, told them I didn't feel ready to go back and GP sent another note. This may have been different because of covid, but it seemed very slack. I definitely needed the note to begin with but I probably could/should have gone back sooner.
We currently have quite a few people on long term sick and based on my experience, I'm wondering how ill they've needed to be to get signed off. Is there any come back on doctors for signing people off too easily, what's their incentive not to just sign every request?