@Jordan – Oooo, yeah, the critical hit deck would not be good for in-party fighting. It’s bad enough when a sellsword cuts off your arm, but the fighter who’s supposed to be on your side? Oof.

Note: When party members fight, Paizo’s Critical Hit Deck is not always a good idea.

The trick to it, in my experience, is time management. Like you said in the post, you need to (as the GM) keep an eye on the other players and gauge when you need to switch gears and scenes. Generally speaking I try to use a 5 minute rule. 5 minutes of one on one can get a lot done, and gives me a hard time frame for jumping groups. I’ll also jump faster if the player is given a big decision, or any time the player’s brain stalls to think. This works as a double nicety as it gives the player time to think while keeping the game moving along at a good clip.

As a player, you need to recognize that everyone deserves a shot at the spotlight. If they sit back when they are given the chance that is one thing, but don’t try to hog the GMs time when they are switching groups. If the GM missed you, point it out, but don’t be rude. Don’t try to over-run the other players for your time to shine. If you really want more time on screen, give your character a reason to stick with other people so that the GM has more draw to go to you (more people = good use of GM time).

I ran a game once where the party was only a party in the barest sense of the word. A sci fi campaign where two people played infantry, 2 people played pilots, one person played a ship engineer, and the sixth played a civilian scientific consultant. It was a great exercise in time management, and it was really interesting that IC wise half the table had no clue the other half even existed aside from in the barest sense of the word. Was good times, at least until the school year ended and no one had the time to continue the following semester.

@Robert – Hey, there were 4 of us, and my character’s butt was still firmly attached when we finally decided to run!

@Kensan_Oni – No, it’s not a crime to go into a store you don’t care for, but I think you missed my point. What I’m saying is that your entire adventuring party doesn’t have to remain attached at the hip like a gaggle of teenage girls at the mall. Unless they really want to.

@Pixiedragon – The “my character is invincible” mindset is a dangerous one, and it often causes trouble when the party is split. For that reason, I think it’s sometimes good for those Bad Things to happen, as a reminder that hey, you may be a big fish, but there’s always a bigger fish. That’s not to say that it should be intentional (“OK, they’ve split up, I’ll spring these assassins on them!”) but if it happens, and it serves them a piece of humble pie, so be it.

@Jordan – While I didn’t specifically address splitting the party within a dungeon in my post, for the most part I think that’s a bad place to split the party, at least to the degree of everyone going off in their own direction. Dungeons are usually designed to need the whole party working together to get through. At most I would split a party in half in a dungeon – one to explore each fork of an intersection, maybe – and then have them meet back up in short order. Bad Things always happen in dungeons, and you do want safety in numbers!

Unfortunately, that mentality is ingrained in our group now even though we’re in a dungeon crawl in a place known as Mt Thanatos. We had. The rouge/assassin slips out a side door the middle of the fight, the ranger wanders off in a daze mourning the death of her animal companion, the dragon shaman tries to use his breath weapon to break down the door so he can go back to town for more supplies, the beguiler hunts for traps in the main room, and the fighter (group newbie) just sits there and shakes his head. The bard had already died of a heart attack/missing character sheet.

It’s fine to split the party, just put reasonable limits on it.

I agree with the possible extra danger for the subgroups Robert mentioned though. In one small session with just the druid and the rogue (not with me DMing though) they both nearly died because the druid thought the DM ‘wouldn’t let us die anyway without the whole party present’ and didn’t use his healing spells. But that probably has more to do with the fact that both players thought their PC’s were invincible.
When it’s possible and what they’re going to do is more significant for the player (or 2 players) than the rest of the group I tend to do a small session in between the big sessions with just the two of them. This way I can also easily give the one player some information the rest of the group doesn’t have. Or each one a different rumour concerning the same thing. Since we play online, it’s rather easy to find a spare hour inbetween to play it out.

It is not a crime to go into stores you wouldn’t shop at together! Solidarity! Windowshopping! Besides, you never know when you’ll find something good that you wouldn’t have known was there, if you didn’t go in and look.

Now this doesn’t mean that it can’t be dangerous to characters to split the party, just that it doesn’t affect Player’s relative amounts of game time