Medium is better

The bigger the better!
or
Small is beautiful.

Small means too much energy is spent on struggling to survive. There is no economy of scale. Furthermore, if there are lots of small independent organisations doing similar things there is usually duplication of effort.

For example, three small churches in one suburb all maintain their building (or set up in a public facility), all do the committee work and paper work and fund raising needed to employ a pastor, and all three pastors prepare a sermon each week. All three struggle to organise a barely viable youth group. Merging into one church which employs one senior pastor and one youth worker would be much more efficient and effective. But, everyone would have to compromise and adapt....

But as organisations grow they can also become inefficient and problematic. "Big" can lead to corruption, bureaucracy, internal squabbling, loss of focus, comfort, and arrogance. Furthermore, big and "successful" Christian organisations with significant resources can attract the wrong kind of people. People who are attracted to "success" and power, rather than people who want to humbly serve and are willing to make sacrifices. People who want to be in the limelight and have their ego stroked. People who want a "career" rather than people who are actually passionate about the mission of the organisation.
[This point is well made in the book Revolution in World Missions by K.P. Yohannan in the context of Western organisations try to hire staff in the majority world.]

So the struggle is to find the balance between big and small. Medium is better.