follow it through to the end

Developers should follow a piece of business functionality through to the end.

Going through every stage of requirements, design, implementation, testing, delivery.
Whatever process you are using from waterfall to agile, it doesn't matter.

The alternative is technology silos where each developer is assigned their own section, which leads to the abdication of responsibility:
"I only did the EJB bit"
"I only deployed the service"
"I just installed the thing"
etc

with no one being responsible for actually solving the business problem.