The Ready State Virtual Mobility Coach is like having a virtual Kelly Starrett in your pocket.
I think your t-spine mobility depends on a lot of things. some of these things like your normal daily posture during standing and sitting can confound any work to mobilize that part of your spine. there could be structural issues too, like the discs shrinking in that area due to previous damage which could inhibit mobility. and then there are poor movement patterns which can lock your spine back up just when you loosen it up.