We've never really needed more than three.
We could have four - or five, or 20 - that's fine - I just don't think that it gains us anything.
Why We Want One Above SSD And I
The workload is fine with two, we just want a suitable number of perspectives and to be able to take a vacation without it all falling on one person. Since the shift to better community moderation, however, we've done that several times without issue (waxy's been checked out for a long time, and SSD and I do have real lives and have been away for a week or two at a time without incident). It would just feel more polite not to have it just reduce to one.
Why Other Reasons For More Probably Don't Help Anything
Time zone coverage is not very important IMO - have we really had problems that have gone out of control in a short time that the community hasn't been able to handle? Users can close and vote to delete and such just fine, so this is isn't a problem we've ever had.
I don't think we need "more perspectives" because "SSD and I think exactly the same." We disagree on topics and we differ on how we'd handle various incidents - you can look in meta on questions where we've both posted and there's a lot of variance. Heck, I disagree with him on the question closure in that other recent meta Q that the OP user won't behave enough to get reopened; if he ever did I'd chime in on it with a different perspective. But people that are expecting any mods to be super different will probably be disappointed. We've had many mods over the history of the site, and the group has always been well aligned -
before I was a mod, when it was Ace and Pat and RC Conley, when it was me and Brian and CRoss, and when it was me and SSD and waxeagle. All these folks are really different people, I bet long timers could read a post from any of these 8 people and guess who it was. But for some reason, once the kool-aid is drunk, we all end up being pretty aligned on how to run the site. Why? There's two factors at work.
- The people who are willing to run for mod, which is generally a thankless job, have a high degree of sense of responsibility and buy-in to the site in the first place. We tried to get a couple folks to run last time who didn't want the hassle. So by the time you self-nominate, you're either obviously in over your head and don't get voted for, or already have a pretty good alignment with major policy issues.
- Once they're elected and get to "patrol the streets" for a while, the remaining happy slappy libertarian theory dries up. Ask SSD about how his perspective changed from just being a high-rep user and becoming a mod. I'm sure he won't mind me quoting him from mod chat from a year after he got elected:
I had a pretty sharp perspective shift when I moved from loud-mouthed regular user to diamond mod; some things are just clearer from here because moderating them underlines practical concerns that were only theoretical from a user perspective.
So for those that think "well certainly more mods will mean changes," and by changes you mean suddenly comments won't be deleted and questions won't be closed and site norms won't be upheld - or that those mods won't sometimes do what they think is best even when people are yelling - you'll probably be disappointed. Once a person with a sense of responsibility gets responsibility, they end up doing the responsible thing. I don't see that as a "lack of diversity," it's called a helpful and constructive alignment.
Why More Might Be A Problem
Well, we need qualified nominees. We had an election just a couple years ago and many of the most qualified people on the site that we specifically urged to run wouldn't. So in the reductio ad absurdum, if we elected 5 more mods tomorrow, would some of those not really be great candidates just because we want to fill seats? But I imagine we can find 2.
The other potential downside is for those who want "less mod intervention" - with more mods, there's going to be more people at keyboards that will feel like they should intervene in something. If they were just high rep users doing it, it would probably be fine, but once it's a "MOD!" then people get into this weird us vs them mode.
And one final one - the concept of more mods got brought up on a recent meta question in response to discussion of a kind of activity that wasted mod time. The answer to time-wasting activities is not add more mods to handle it - we're exception handlers not garbage-men. I really wouldn't want "well there's more mods, so, they can handle it" to be a justification for poor site behavior or hygeine.
So to me, there's not a huge problem with more, just not particularly any benefit, so why go for "bigger government" unless there's an actual need? Remember high rep users can do 95% of what we can, and do, and should...