That might be more of an issue with Techstars than being a solo founder (I've been through Techstars as a solo founder. I'm also a YC alum).
Techstars has lots of talks, sessions, and pitch practice. YC has almost none of that - one dinner a week, otherwise, a complete focus on product and customers.
Agreed. I started out solo in an incubator and had to be RUTHLESS with my time. Basically didn't really make use of the mentors / sessions / etc - too busy writing code / making sales calls. Didn't spend time networking with the other startups - too busy trying to network in my industry. Didn't spend time on pitch competitions etc - too busy trying to find real investors who knew me and knew the space.
I've since added a co-founder, but we more or less still operate the same (probably a bit to our detriment).
Techstars has lots of talks, sessions, and pitch practice. YC has almost none of that - one dinner a week, otherwise, a complete focus on product and customers.