Reliability is competence repeated on schedule.

Being capable once is a demonstration. Being capable on a predictable schedule is what people can build on, and it is a different achievement, requiring systems and habits rather than ability. Most reliability failures are not failures of skill but of repetition.

Look at where your quality varies and ask what changes between the good instances and the poor ones. Usually it is preparation or timing. Fix that and the competence becomes something others can depend on.