I actually enjoy having my real life consumed by a fantasy one, but I recognize that not everyone does. (Lut, for example, dislikes having my RL overwritten by my VR. =D )
There are various factors that are likely to make my next game naturally have less traffic than the previous ones:
* I'm likely to set aside hours where I won't be posting -- probably from 8 or 9PM to 7AM CDT. This will ensure that Lut has my attention for a few non-sleeping hours every day. :) This won't be hard-and-fast -- I might toss off quick emails just before bed -- but I won't be spending four hours every night writing email for the game, either. Which, um, I have been known to do in the past. ^_^;;
* Since the game will only encompass 24 hours +/- of in-game time, I expect little if any time-bubbling. When Honored stopped having time-bubbles, list traffic dropped from 150+ emails per day to 30-. There were other factors lowering traffic on Honored at that time, though.
* There'll be fewer PCs in this game than in Honored (which started with six) or +Terrible Butterflies+ (which started with five). I'm expecting to cap this game at four PCs and there's a reasonable chance I'll run with fewer than that. I may have other people playing NPC-ish roles if I get any volunteers for that. I'll talk about this more in a separate post.
Another point to bear in mind: "number of posts per day" is the easiest metric to pull out, but it's not the most accurate one to describe volume. Some PBEM posts set scenes or contained responses to several different previous posts, and these might have several hundred words of new text. Others were only a sentence. I'd guess that the typical PBEM message is about the same length as a typical pose on a MUCK -- maybe a hundred words. I'm thinking that a hundred posts would be about equivalent to a chapter in a book or a short MUCK log.
To sum up: I really don't know what sort of traffic my next game will generate. The issues posed by traffic levels vary, too, depending on player habits and expectations (both IC and OOC). Some examples to consider:
* X, Y and Z are having an active conversation one evening when they're all at their computers. A fourth PC, played by A, is technically in the scene but for whatever reason he's not checking his email so his PC isn't talking. The ensuing conversation is similar to a MUCK log, with each comment in its own post. The next morning, A checks his email and sees 90 new messages. If you are A, will this bother you?
* A responds to 20 of the messages from the flurry last night, inserting his PC into the conversation and re-starting some discussions that X, Y and Z had settled. If you are X, Y or Z, will this bother you?
* The party leader goes with the plan X, Y and Z worked out the night before. The GM starts responding as if it were unfolding, even though X and Y would like to change the plan based on A's insights. Is this a problem?
* Does your reaction vary based on the time lapsed? For example, what if the conversation between X, Y and Z takes place over three days, and then A responds, as opposed to responding 10 hours later? Does it matter if A is regularly delayed in responding, or if this is a rare occurence? Likewise, does it matter if X, Y and Z are often much more active than A or if that only happens now and again?
* Examples of how IC expectations can impact this: if A is playing a PC who has no background in the subject X, Y and Z were discussing, A will care less that he "missed" the conversation than he would if his PC were the party expert. If X's PC is a very cautious sort who hates taking action without thorough consideration first, he will probably be happier about having A extend the conversation than he would if his PC were impatient and eager to get to the action.
I want to note that feeling some or all of these things could be annoying is perfectly reasonable and normal. Yes, it's a game and it would be lovely if all of us could be sublimely indifferent to all of its quirks and oddities, but the truth is if we didn't care about such things we probably wouldn't care about playing at all.
What I want to do now is try to set expectations of what's "normal". Some possible questions for those thinking of playing: what volume of traffic do you think would be too much? Just right? Not enough? (You can answer in terms of either "for the whole list" or "per participant", whichever you feel is more accurate.) If traffic on the list goes over what you consider "too much", how would you want to resolve that? What if it's too little? How much of a concern to you is this likely to pose -- ie, would you be okay if you're making one post a day while others do ten, or vice versa?*
I know that some of you have little experience with PBEMs, so this is asking for guesses in the dark. And the truth is even people with some experience aren't going to know what will work this game. So I'm not going to be surprised or offended if you get into playing and find your feelings change. This isn't the final word, but a starting place. Also, if some of you are thinking "10 posts a day is too many" and others "less than 30 is too few", then I'll know now it's probably better not to put you in the same game together. :)
* You don't have to answer all of these, and feel free to make comments on any related topics. I'll answer these questions myself in a later comment to this post, but I want other people to give their answers first so they'll have slightly less bias. :)