In the comments on one of my recent posts, Craig A. Glesner reacted with surprise that you would play Novarium with multiple characters under your control. So this post is for you, Craig. This is why you would want multiple characters.
Reasons for Playing with Multiple Characters in a Seasonal Rotation:
1. When you have a single character, anything that disables your character for more than a few days becomes seriously problematic to the game. You take a deep wound to the chest in real life, you are not going to be back in the action in a few days after your HP goes back up. But if you have multiple characters, you can literally send someone off to rest for six months while one of your other characters steps in to fill the gap. The same logic allows your character to do research in the laboratory for a few months, spend a month building a structure, etc.
2. When you have a single character, all the classes/options must balance. You cannot have a clearly superior class because then everyone would take that class or be obviously inferior. However, if you allow multiple characters in a rotation, then everyone can have a single superior character and a handful of ancillary characters that support that person. Players will be willing to accept temporary imbalance in power dynamics within the party when they know that in a few sessions they will be playing their powerful character and those playing stronger characters right now will be back as weaker characters at that time.
3. When you have a single character, and you are not able to make the session, there can be a shortage of manpower to go on the adventure. However, if you have multiple characters then one of your minor characters can be thrown into the mix under GM control, or under the control of another player. Or another player can run two of their characters and none of yours. Or whatever you want. It is flexible that way. Also, as a variant on this, you can easily run a solo adventure with a character you are not using during a time when the party is going somewhere else.
4. When you have a single character, death is very painful. You may act conservatively to avoid death, and thus avoid a lot of fun as well. However, with multiple characters this effect is much less pronounced. You can made the hard choices and lose the character, but still keep your cool.
5. When you have a single character, splitting the party can be very painful and difficult. With multiple characters, it is very easy and can allow you to tell multi-threaded stories that you might otherwise have a very hard time doing.
6. When you have a single character, you are much less likely to take disadvantages that result in time away from the party; love interests, family relationships of all types, deep friendships with NPCs, etc. Your characters never settle down. They tend to remain a group of armed homeless people with no ties to the world around them. With multiple characters, these problems are much less pronounced. You can afford to send one of your characters home to take care of their sick parent for a few seasons. You can afford to give someone some time off with their loved one. And so on.
7. When you have a single character, everyone is always assumed to be in the party. Challenges thus always have to be on par with the party. If your gang of 6th level D&D characters come across a band of brigands, they better be damned strong brigands or they are just going to get cut down like grass. With multiple characters, the party might consist of only one or two powerful characters and the rest are much weaker. This allows you to dial up or down the danger level without worrying about TPK.
8. Speaking of TPK... with multiple characters, there is never a TPK. There are "lost expeditions."