Back when I was Lord of the Viridian Entente, I made a note of it to bring new faces into the upper-echelons of government. At the time of my ascension, the Entente had always been ruled by the same old guard from near its inception, which caused problems. More than anything, I blamed groupthink for the policies that led us to isolation and annihilation in the Green Civil War. Bilrow may have been responsible for pulling the trigger, but it wouldn't have been possible if not for countless missteps on our part. I also worried that the general membership would grow frustrated by immobility. Without a chance to rise through the ranks, promising talent might up and relocate to other alliances or found their own in order to sate their desire to have a turn at the top. These things were of immediate consideration when I took over during the Second Viridian Era: my Lordship was the result of a massive government exodus and positions needed filling. So rather than tap the Ministry of Awesome, a roster of Viridia's old leaders kept on hand for advice and pinch hitting, I reached down and brought up people who'd never been in high government. There were some growing pains, but the hungry youngsters more than proved themselves. It was my first decision as Lord and probably my best.
The subject of turnover pushed its way back to the front of my mind while watching the ODN elections. OsRavan had served as Secretary General of the Network for an incredible span of time and the general membership was growing restless about it. It didn't matter that he'd performed capably and led the ODN from pariah status to core member of C&G; the members didn't like the idea of one man staying on top for so long. The following election, at least from my outside perspective, appeared to be a referendum on that subject. The result of the election is ultimately inconsequential to my point, but rather I speak of it to show how democratic alliances can use their oft-criticized institutions as a channel to force turnover and keep the membership involved. Though the turnover leads to foreign policies of questionable stability, and democratic turnover can lead to very bad leaders (Vincent Xander, Ramirus, etc.) I think the internal benefits are ultimately a good thing.
Non-democratic alliances do not have such checks on term length. Leaders can stay on top as long as they want. Leaders can choose to regularly shuffle high governments or choose to keep things in place as long as possible. It falls entirely on them to try and read the general membership and make decisions accordingly. The problem is that I don't think many non-democratic leaders actually stop and think about term length. Most folks will just favor stability over change. And while stability has its advantages, on the whole I believe this to be a bad choice, both for non-democratic alliances and for CN in general.
CN is replete with stories of old leaders guiding their alliances into doom. Pacifica pre-Karma is perhaps the best example of this. The NPO, led by the same Emperor and Imperial Officers since forever, grew increasingly stagnant in diplomacy and internally. I've heard many people complain about the good ol' boy nature of Pacifica's governance and the overwhelming power of its Imperial Officers. The stagnation at the top promoted groupthink and, in the end, the NPO made horrible decisions until it was ruined in the Karma War. For other examples of failure encouraged by leadership stagnation, look at the already mentioned VE pre-GCW, GOONS pre-UjW (leadership stuck around too long, got bored, and pushed envelopes too far), or NpO pre-WotC (though Assington served a stint as Emperor).
Groupthink isn't the only problem that grows with stagnation in turnover. Bringing in new leaders from time to time can help an alliance shed past grudges and make new diplomatic moves. That's not a guaranteed benefit, as people are more than happy to argue that new leaders are just as responsible for the sins of old leaders, but in my experience I've found it to be nonetheless effective. Appointing new leaders at the very top also helps prevent an alliance from becoming a mere cult of personality. If you have the same figurehead for too long, it may undermine an alliance's ability to function without him or her. That was Egore's most notable concern back in the First Viridian Era, that the VE would just be his cult of personality and die off whenever he decided to call it quits (a concern that led to my rise to power in the alliance). Alliances should always have an identifiable face or it becomes inconsequential (lookin' at you MHA), but if the face never changes it may have dire internal consequences. I hate to think of what the impact would be if Archon ever formally stepped down, for example. I'm not sure GOD could continue to exist without Xiphosis at the helm. Nobody could fill the shoes.
Finally, stagnation at the top is terrible for CN as a whole. For one, it results in the bifurcation of the game: there's the game leaders play and the game followers play. This is true no matter what, but giving new people a chance to enter the leader game blurs the line in a beneficial manner: the new leaders develop an appreciation for the leadership game and the followers gain new, knowledgeable players in the form of former leaders. Former leaders may be loathe to return to the follower game, but I've always found the challenge of figuring things out from a general member's perspective to be fun. Second, stagnation in non-democratic alliances encourages the plethora of microalliances we see today. Since people can't climb the ladder in the blue-chip alliances, they leave to go start their own. This is an unqualified bad. The stagnation at the top is reinforced as prospective replacements leave. Meanwhile the treaty web grows more complicated as new microleaders try to wrestle into the leadership game. They almost invariably fail and simply become proxy states of other alliances.
So if you're in charge of a non-democratic alliance, look at your present roster. Is it more or less the same as it was a year ago? If so, stop and actually discuss the merits and detriments of this fact. If you choose to stay the course, that's fine, but you may find shuffling things to be surprisingly tantalizing.