A lot of you seem to be highlighting that day/night systems are usually disabled, and they are. I don't believe that it is because of the concept itself, rather because effects wise they are done in a pretty bad way. I don't think I've yet to see a day/night cycle that didn't just slap on a dark overlay, and simply making the players' screens darker is obtrusive. Here is an example of what we've been kind of limited to on Graal servers as far as "night" goes, and beside it what I feel is a much more classier and less obtrusive effect:
Yeah I don't script so I don't know how possible transitioning something like this would be, and obviously I wouldn't want it to change that fast, but I think it comes across way better; actually making the tiles look like they're in a night setting. If I couldn't achieve something like this then I'd rather not have a day/night cycle because I have yet to see an overlay effect that looked aesthetically good.
Day/Night cycles can have many perks to them, but overall I think they really assist in the immersion and pacing of a server and its gameplay. I have played Animal Crossing and fished in the morning, then fished at night, and knowing that there are going to be different types at different times is exciting. It doesn't throw everything at you at once, and this is what a lot of the servers do already, especially those with quests; everything is open field, you rarely have to do something else to gain entry to other branches of quests, and therefore there really isn't any kind of pacing. Pacing is important because it helps you bring out hours of gameplay, and contrary to what I think people are going to say, doesn't always mean stretching things out so it's slow as hell. If I know a graveyard lights up at night and I'd be able to quest in it, I'd have an opportunity open to me at a specific time, rather than just going there and doing it when I like. For things like Era, it would allow you to pace your economy, and imagine what kind of people come out at night in a real world setting
. The opportunities are pretty big, but nobody has really used them.
I'm not sure about a 24 hour cycle, because like others have expressed concerns about, I wouldn't like to log on and play entirely in night and have to wait up for hours to get into a decent setting. Depending on play time, people could only come on for a couple of hours each day, and to be playing at night every time you log on might come across as unwelcoming. I like your idea about a 3 day cycle per real day Spark, but that might be too many days? I don't know, but another concern I have is not being able to keep track of days through a calendar because of this through having 2x the amount of days. I think that might be the most suitable however.