Yes, we absolutely can, and that is all we would ever do.
However, in older exhaust systems, the most likely cause for needing a section replaced is that it has developed a leak through a hole or crack due to corrosion.
As such, in these circumstances, we cannot always be certain of achieving a strong seal between the newly replaced section and an existing corroded section/s it is connecting to. Should this be the case, we may need to quote to replace additional exhaust sections to be sure or deliver your vehicle back to you leak-free and without any exhaust system issues.