Are moderation elections held on a regular basis, or just when the need of more people arises?
And, related to this, the moderator status is held for a set limited timeframe or forever?
Just for clarity, I ask for the sake of curiosity, I'm not interested in becoming one :-)
Are moderation elections held on a regular basis, or just when the need of more people arises?
Moderator elections are held as the need arises. If the current moderator team feels like they need more help, or if the Stack Exchange community managers see a need for more moderators, then the moderator team can request an election. A moderator election may also be held if an existing moderator needs to take an extended absence from the site, or if a moderator is hired by Stack Exchange to become a full-time employee.
Due to the steady increase in activity on the site, the elections are also somewhat regular, and have occurred about once a year for the past two years.
[Is] the moderator status is held for a set limited time frame or forever?
In most cases you're a moderator for life. If a moderator is inactive for an extremely long time (typically at least 6 months without logging in and 1 year without any moderation activity, and if nobody can get ahold of them via email) then they may have their moderator access removed, but it can theoretically be reinstated if they return in the future. Moderators are also occasionally hired by Stack Exchange to be community managers or developers, in which case they are no longer technically a moderator, but would retain moderator privileges on all sites.
From the March 2013 moderator newsletter (they're public):
Calling for Elections – Need More Help? Just Ask!
In the past, the community team was monitoring sites to determine when they needed more mods in order to maintain good coverage. Recently,we realized that we’re usually not the people most qualified to know when there’s a need. You are!
Going forward, the main trigger for us to consider holding elections will be the existing mod team telling us they need more help. As of now, any time you feel that your site is understaffed, either because the workload is increasing or because there aren’t enough active moderators, please get as much team consensus as possible, and then email the Community Team to let us know how many additional mods you think make sense to add.
After reviewing these requests, we may suggest a different number, or offer to reach out to any less active mods first, etc. But most of the time, since you’re in the best position to tell us what your team needs, and we’ll work with you to get an election scheduled.
Moderators don't have a default 'term of office' or something like that. Of course, they can always step down. And this post on MSO described the process of removing a moderator.
