I really enjoyed reading @adactio article on how he writes alt texts and how to make them useful and not off-putting.
That doesn’t mean it’s okay to have the same alt text for each image—they are all still different. But after I had that realisation I stopped being too hard on myself if I couldn’t come up with a completely new and original way to write the alt text.
And, I remind myself, writing alt text is like any other kind of writing. The more you do it, the better you get.