However these are not "mini-churches" or house churches for the reason that there are only churches in the New Testament, including or especially house churches, and these are no "adjuncts" to anything. Rather, NT churches are independent and autonomous entities, answering directly to the Lord Jesus Christ (the body answers to the Head) via the revealed Word and subject to the guidance of the Holy Spirit.
In Acts 2:42 we find the ordinances of the first church–teaching (the apostles' doctrine) and fellowship, the breaking of bread and prayers. In Acts 2:46 we find that they also broke bread "from house to house." But was this activity planned by church leaders? There is absolutely no reason to think so. Rather, the Holy Spirit directed the saints, as He did in the meeting on the Lord's day, to private fellowship outside the full assembly.
The "scheduling" by men of cell groups is the corollary to planned worship on the Lord's day. Both are scheduled by men rather than the Spirit of God.
The second accommodation is made in churches which hold separate and consecutive meetings for the Lord's table and Bible teaching. The Lord's table meeting, in addition to remembering the Lord and His sacrifice, is ostensibly the place for the exercise of speaking gifts. However it frequently turns out that little teaching, exhorting, prophesying, or ruling is done in these meetings, but instead the teaching is done by one man in the "teaching meeting," exactly as it is done in the clergy-led churches.
Neither of these accommodations line up with the indicated New Testament practices, when "the whole church be come together into one place." I Cor. 14:23. It is better not to make "accommodations" but to do what the New Testament teaches and to imitate the New Testament practices. Paul wrote to Thessalonica,
Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.
---II Thessalonians 2:15