Each calf. It helps to place the foot you’re not stretching in front of the one you are stretching. I had terrible plantar fasciitis for years. I went to several podiatrists, paid for expensive inserts etc.

Finally stumbled on a YouTube video that showed me how to do that twist when I stretch my calves and it made the pain go away for the first time. Doesn’t even hurt in the morning anymore and that was always the worst.