I would say "Whatever works best in your situation". And "Be consistent". And "Document your code well". And possibly even "Document your HTML well".

For me personally, I would use different templates for different outputs. But if the logic for different outputs is the same, I would try to have that at one location, rather than having to maintain two identical pieces of code or HTML at different locations. Your templating system may or may not allow macro's or include's.

But without more to go on, there's not a lot more to day, I don't think.

Liz