The same classes are offered. The same outreach is conducted. The same music is recycled. This pattern can set in for many years, but eventually the parish groans for a change. The old ways just don't work as well as everyone remembered.
Christians also fall into the same pattern.
It's not as much effort to go through the motion of the church year, and attend the same familiar programs and see the same faces. Its nice not having to flip through the prayer book to find one's place after you memorize all the prayers. Individuals as salt share their gifts and engage in some ministry, be it teaching, hospitality, prayer, or some other. If that's all they ever do or are known by, then eventually the very things which drew them to the parish repulse them. Eventually, they want nothing to do with teaching little children or singing in the choir.