Yes, I should check the hanger alignment. I don't have the tool, so I'd have to take it into the shop, which has an extremely high inconvenience barrier for me. I'd love to DIY like this, but I don't have a drill press.
Dave Moulton's Blog - Dave Moulton's Bike Blog - Aligning a bent derailleur hanger
The cassette, from left (inside/biggest) to right is:
spider of 3 cogs, with built-in metal spacer on the right
spider of 3 cogs, with no built-in metal spacer
plastic spacer
flat single cog
3 more single cogs, with built-in metal spacers on the left
lockring
My shifting behavior is such that it's hard to downshift into the granny, and easy to upshift out of it. It's extremely slow to upshift to the outer cogs, but downshifting is great. This tells me that the cogs on the right are too far to the right, and the cogs on the left are too far to the left. So I wanted to make the spacer in the middle smaller so they'd get closer together.