I think it’s actually a bit more nuanced than that, see: https://space.stackexchange.com/a/45894 https://space.stackexchange.com/a/45894 Basically the SRB had

I think it’s actually a bit more nuanced than that, see: https://space.stackexchange.com/a/45894 https://space.stackexchange.com/a/45894 Basically the SRB had multiple modules and some were more reusable than others, so some got recovered and refurbished a lot more.