First off, @
ccs - post 65 is completely full of win. Love it!
I agree with most of this.
Point 4: I see nothing wrong with a PC being untrustworthy and-or having a separate agenda from the rest of the party. The best ones are where a player manages to put an enemy PC into the party, has it run with them for a while, then after a couple of adventures gets it out so it can report back to its real friends. This doesn't happen often but it's cool when it does.
Point 6: Disagree most of the time. I'll run what I'm given, when it comes to split parties or solo scouting or whatever. If the timing works out such that someone goes solo just at session's end then that player and I have a perfect excuse to spend an evening that week in the pub. Or, I'll just run it by note during the session, while the rest of the party go on doing whatever.
If I get the sense that a player is repeatedly doing this simply to hog the stage and-or my time as DM I'll start paying less and less attention to their solo missions...I can be evil that way.
Worst case scenario is
when the entire party goes solo. This happened to me a month or so ago: a mid-combat wild magic surge teleported each creature in the room (that's 10 party members and two opponents) to a completely random place in the (very large) dungeon. So now I've got ten solos to run, along with figuring out where the opponents wound up. Very lucky for me in that this happened close to when the session would have ended anyway, and so I did the solo stuff by email* during the week. By next session a few people had reunited...and again I got lucky; the characters belonging to the players I knew would be missing that session were still on their own, so I ran with a reduced crew whose characters had either reunited or were within a room or two. By session's end everyone had been scooped up with (amazingly) only one casualty. (they'd already explored quite a bit of the complex and by sheer luck many of them went to relatively safe places)
* - what this taught me is that I will never ever ever EVER run a full campaign by email. Bleah!
Lanefan