I believe that it is wrong to leave a church without established elders. I believe that it is wrong to consider a newly ordained elder as established. And, I think it is wrong to ordain more than one elder at a time. Allow me to expound briefly on each of these individually. (Update: I wrote that a while back and have since seen it desirable to tweak these points a bit.)
It is… less than optimal… to leave a church without established elders. First, a church needs elders; not itinerant preachers, but elders. A leadership vacuum will suck in all manner of vice. Second, solid leadership and harmonious brotherhood rely heavily on seamless and natural transition of authority. The church that is subjected to abrupt changes in leadership will always struggle in these two areas, and many will never completely prevail. Third, the example of the apostles is to ordain elders before leaving the church, Acts 14 and Titus 1 not withstanding. Paul did not leave the churches in Acts 14, he was forced out of town. The record is silent as to the churches of Crete, but if one can assume that he left on his own volition, it is equally valid to assume that he did not. Obviously in extreme cases, like those Paul encountered in Acts 14, it is unavoidable to leave a church without elders; however, to extrapolate that into a common practice is specious.
It is… naïve… to consider a newly ordained elder as established. First, every ministry requires an apprenticeship, not just evangelists. There are too many things that cannot be taught, they can only be learned. We have seen firsthand the devastation of not enforcing an adequate apprenticeship on evangelists, and I believe we have seen the same with elders and deacons. We slap a sheriff’s star on their chest and a six-shooter on their hip and bid them “fare thee well”; and wonder why they become either cowards or tyrants.. Apprenticeship is practiced throughout the scriptures. Joshua with Moses; Elisha with Elija; the Apostles with Jesus; Timothy, Titus, and a host of others with Paul; and that is only to name a few more prominent examples. Second, the men we are ordaining have never been in charge of anything in their lives. Not even their families in many cases. So you take an hitherto AWOL soldier and make him a five star general, and wonder why they struggle to couple confidence with humility; authority with service. Doctrinally they are ready, morally they are ready, in almost every quantifiable way they are ready–and yet they are not. I have heard the rhetoric question too many times, “What more could I possibly teach them?” It isn’t what you need to teach them, it is what they need to learn from established elders: The subtle yet vital details–donning authority lightly, understanding limitations, appreciating differences, accepting criticism.
It is… misguided… to ordain more than one elder at a time. Being co-elders is much like marriage. Evangelists don’t appreciate this because once they finish a work together they are free to split up, no hard feelings. Elders don’t get that luxury, they are stuck for life. Therefore, it is only fair that each elder have a full and informed say on who they will work with. Also, it is helpful that there be a measure of deference between elders, as in accordance to Peter’s instruction that while all the elders are subject one to another, the younger should submit to the elder. It isn’t a hierarchy, but a deference due to their experience and wisdom.