When researching various models of small group organization and structure, many pastors adopt a model before they have started their first group. What's wrong with this?
1. It puts the visionary's focus on a structure, not the member's values that make just about any small group structure work great. Frankly, if one's members are reaching the lost and discipling them successfully, any small group structure will work well.
2. The structure chosen in advance cannot take into account the actual and ongoing needs of the ministers (members) in the groups, making them feel as if they're a new cog in someone else's clockworks from the beginning.
3. Choosing a structure in advance promotes a false sense of security, which keeps pastors from experimenting with or prototyping various models before deciding upon one.
The smart pastor ignores the hype around the models written about or those featured in mega church conference plenary sessions. He focuses on developing a healthy biblical community that experiences the presence, power, and purposes of Christ. Out of this, he will see what leader to coach ratio will be most profitable for his church at that time in ministry.
A great illustration to drive home this point would be buying a suit out of a mail order catalog. The model looks great wearing it, but everyone knows it's gonna look horrid on you once you take it out of the box and try it on. A man's suit needs to be tailored to fit properly, doesn't it?
Don't wear other church's clothing. Develop your first groups, invest your time ensuring they're healthy and growing, and then add the support they need in the way of training leaders and inserting coaches over groups. Your model will then be your model, not another church's model you tried to replicate poorly.
If you must replicate something from another church, figure out how they disciple new believers into spiritual maturity and make it work with a handful of members. When you refine this, you'll be well on your way to a successful small group ministry.