I'm never tsundere for Kyoani. Never really was fond of the studio, though I don't flat out hate it. Disappointment considering their technical skills in animation is a better phrase. PA Works is what I am tsundere for.
And you must be kidding me when you said Sound Euphonium ep 1 > Tari Tari. Tari Tari was great from start to finish and I loved it first episode though not as much as HSI's 1st ep which is amongst be the best pilot episodes in the genre. Too bad that was inconsistent.
I'd even say Hyouka was better, though as we all know that was a slow starter.
I could be completely wrong but I've always imagined that as the senior animator at PAW Sekiguchi gets handed the shows producers have the most faith in or at least the ones they consider more important.
Production of HSI was already under way as Angel Beats was airing so she hardly worked on it for example.
One thing that's very much a coincidence but kinda cool is that when studio Banboo does the backrounds you end up with a trio of: True Tears, Uchouten Kazoku and Shirobako (which is my personal top3) while studio Easter did the rest.
You can tell the styles apart, Banboo is more impressionist than Easter.
Also keep in mind that Sekiguchi's job is to adapt other people's designs (tanu for Tari Tari, Ponkan8 for Shirobako etc...) only time she actually designed them was True Tears because the anime designs look nothing like the game designs.
Why you don't want best girl working on a show is beyond me, if you see her name on the staff it means PAW is actually trying, look at your PAW show ranking
Number of Sekiguchi shows in your top 6: 5
Number of Sekiguchi shows in your bottom 5: 0