In both my L5R and Star Wars games I have no problems with splitting up the party whenever the situation calls for it. Over the past several years I've kind of specialized in "dynamic grouping" complete with starting my L5R game with none of the PCs connected to each other where the main focus of the game is the setting and the people in that setting. That said, there are pros and cons to every type of gaming, and today I wanted to talk about some of the pros and cons to having a split group.
Con - Time Management Is Hard
The biggest con and the biggest problem most GMs run into with a split group is that it means you have to be on your game with time management. Bad time management when the group is split will result in someone or several someones just sitting there, doing nothing - or having no character development time - while the focus is on other players. Because of this you want to make sure you switch focus regularly, and before people get too bored.
Pro - You Can Leverage Your Group For NPCS
While this doesn't work with every player, most players are just fine with taking up the role of an NPC and injecting some added life to a scene. This is a great way to keep players involved in the game even when their character is off focus somewhere else. Even better, with some good notes players will react in a lot more varied ways than a GM will with an NPC which can make things go from good to great. Do it enough and you can have players who regularly depict particular NPCs and a way to at least keep the players involved even if their character is indisposed.
Con - Communication Becomes Problematic
Despite best intentions and interests, players are often really bad at communicating relevant details to each other. I can't tell you the number of times I've run a game where the PCs were doing some sort of operation only for Group 3 to not tell the other groups that not only had they made contact with the enemy and taken some out, but they had been made or some other key detail that changed everything didn't get communicated.
This can also be problematic on an OOC level because sometimes Sarah gets stuck on how to proceed and though Luanne's character isn't there, nor does she have a way to communicate with Sarah's character, she wants to help and throw ideas across the table. Sometimes this can be problematic because it helps Sarah in something she should be doing herself. Other times it is problematic because Sarah (or the player in question here) gets upset and annoyed at everyone suggesting things and not letting her figure out her own character's way of handling things.
Pro - It Is Easier To Challenge The Individual And Show Group Strength
One of the greatest things about splitting the party is that it removes the strengths of certain characters from the group. This in turn lets you challenge and learn about a character by prodding them in areas of weakness that other members normally cover. How does that warrior deal with a locked door? What does the rogue do when confronted with magical items? How does the mage deal with the barbarian trying to smash their head in with a barstool?
On the other hand, this can also - in the same way - show how the group works together. Once the party sees how burdensome traps and locks can be when the rogue isn't around, if nothing else they'll have a reason to keep the rogue. The same for everyone else and their areas of expertise.
And Vice Versa
All of these cons can also be pros and vice versa depending on how they play out. They can also very easily lead into each other. Having a player play an NPC can lead to an NPC stealing the spotlight and moment from the PC who should be the focus. Challenging an isolated PC can cause bad time management. Bad time management can entice others to be more active with their characters and keep them doing interesting things to be worthy of screen time. Everything is a trade off, but there are definitely perks to being able to have the party split up in your games. Not the least of which is it gives everyone a chance to breathe, and more time to shine as an individual when they don't have to compete with the rest of the group.