Smaller churches are often those that are just starting out on their own religious journey, and there are few members to support the church. For those congregations, the price of a full-time preacher might be too much. Many of them begin with a few worship services, and their preacher is only engaged to work a few days per week. It might not be ideal, but it is a good way to begin a new church in a new area.
Working only part of the time as a preach means that income must be found elsewhere, and many of those who work in small churches have a regular job. It can be a good way to connect with the congregation, and this type of church official understands the lack of time the members have for religious observance. It can help them bond with the members, and it can help the members bond with each other as they are unable to depend on their pastor being available at all times.
It might appear that there is a lack of religious commitment, but many of those who preach while holding another job have found their congregation understands their need to help others. Their calling might not translate into a full-time job, but their dedication is always with them. Many of them spend an extraordinary amount of time outside of their regular job working with their people, and this lends incentive to members to help alleviate their burden.
Preaching only on weekends or a few days per week can be a good way for a congregation to reciprocate in good projects when it comes to supporting their church. They do not have someone readily available to lead them in religious matters, and it can make them take on a greater role in finding their own answers within their faith.