^A lot. Rebrandings are very expensive. A friend of mine bought a few local video game stores and to get them all under the same umbrella it cost $100,000 just for signs inside and out, logo design, marketing materials, website changes etc. Most exterior signs had to be different sizes since the units had different sign spaces -- lit, unlit, some were lenses while others were 3D.
Back when Speedway acquired Super America the changeover took years. And you can still kinda tell where a Speedway used to be a Super America.