I am the foremost authority on Jeffrogaxian Time Keeping (JTK) vs Variable Time Keeping (VTK) because I've run and am running two campaigns rn using ACKS and all it's complicated campaigning rules. These include fielding armies, leading military campaigns, building keeps, crafting spells, running trade ventures, running crime syndicates and all the other things that make a dnd campaign more interesting than just delving dungeons and going back to town. One of my ongoing campaigns uses JTK and one uses VTK.
As the authority, and as a giving man eager for the people to enjoy superior dnd campaigns, I am composing this blog poast to explain to you, the people, how they differ and why JTK is the better of the two.
First lets define them.
VTK is method of dnd ttrpg etc timekeeping with which most DMs and players are familiar. How does it work? The main thing you'll be familiar with in VTK is that if you have a 4 hour dnd session and run out of time whilst your PCs are deep into a megadungeon it's nbd. Your DM hits the PAUSE button and you and he pick up where you stopped next session. Some version of VTK, like my ACKS Greyhawk game, allow PCs to FAST FORWARD through time for whatever reason they wish. These might include fast forwarding so the wizard can create a magic item that takes 1 month to create. During that time I'd say "hey what are the rest of y'all doing in that month" and we hash that out at the table.
JTK is different in that players can NOT pause the game between sessions. My e-fren Chanticleer describes JTK as follows:
"During a campaign sesssion, players have some control over the flow of time. Players can spend their time traveling, exploring, fighting monsters, resting to regain spells, or in one recent session my players spent an entire week of in-game time casting glyphs of wardind to lay their aboloeth trap in the sewers. However when the game is not "IN SESSION", players DON'T HAVE CONTROL over time. When the players aren't playing the calendar of the campaign setting moves forward in sync with the real world calendar. "
Chant gives an example but I'll give one of mine so there are more out there for higher variance of reader grokking. Imagine the players began to explore the wilderness on July 7 and it took them ten days. They come back to town on July 17th. My next session is on July 14th. The PCs involved in the above exploration can't be played on the July 14th session because they were busy doing things that day. They won't be "done for 3 days".
When you institute JTK you end up with a major paradigm shift on how players approach the game. Guess what kids, you can't PAUSE in the dungeon so you better complete your delve and get back to a safe zone before the end of the session time. Some players and DMs don't like this, claiming it tethers the PCs to civilization or that it limits their choice.
In some ways, perhaps. But the gains are massive. Swole.
In practice the players realize that if they take just a day or 2 to delve during a session they have 5 days their PCs are existing in the world before the next DND session. They don't want to waste that time so they start making "Downtime Requests". Those are things that Mr Wargaming describes as things that respectable adventurers should be doing but which don't really warrant session time.
Such as: hiring mercs, burglarizing petty nobles, carousing, rumormongering, making magic items, assassination... etc
Players will start jumping at the opportunity to do these things because they don't want to WASTE that downtime between sessions. In a VTK campaign they often won't have time for ANY of that unless and until they are able to convince their other party members to slow down and let them do those things.
In practice this often means multiple players bored at the table as Joe the Mage describe the magic item he's going to create. Or Swole the Barbarian rolls dice and counts gold pieces to figure out how many infantry he can hire this week.
My Greyhawk ACKS campaign in VTK does the above. These are players who have been friends since middle school so they work things out pretty well about when they're going to take breaks from adventuring to do "upkeep" type stuff. It goes pretty well for us. But a JTK campaign is going to inspire players to do those things more readily.
Running a VTK with big elements will mean a DM has to be quicker on his toes. If they want to spend 2 hours of session time hiring infantry to go wandering around looking for randomized trouble (lairs etc) you need to be on your A Game as a DM and have lots of modular materials ready. I use various Books of Lairs as Dynamic Points of Interest as per ACKS GMing advice.
This is MUCH easier on the DM using JTK because he will only need to "fake it" for a couple hours and then he'll have another week to do some more detailed prep if the players decide to push one with that plan next session.
So ease of DMing is one point in favor of JTK. Another is that a JTK campaign can have COMPETING PLAYER CHARACTER PARTIES.
My ACKS Auran Empire Campaign has two different PC parties. I run one group of players weekly online and I run another group every month or so face to face at my home. The player parties have already swooped each other's hooks and such a few times.
This is not possible in VTK campaign. If Group 1 pauses time in a dungeon does that mean Group 2 is stuck paused as well? Silly. Two points in favor of Jeffrogaxian.
Last but certainly not least is JTK Campaigns can have Chantsonian Patrons. You're going to have to check out my last session report for an explanation of this one. But the bottom line is, with JTK, you can have wargames between massive factions happening AT THE SAME TIME as you run normal dnd sessions. The results of those various wargames (or syndicate street battles or whatever) will echo into the dnd sessions.
Check out here where I had my dad run a wargame against one of the major NPC villains wherein he controlled one of the major NPC good guys. This isn't feasible in VTK because how would I gauge the timing of the military campaign if my PCs can PAUSE Time in the megadungeon? Or if they can FAST FORWARD THE WHOLE UNIVERSE. I can't!
So let's conclude. Jeffrogaxian Time Keeping is superior because it makes downtime easier for a DM (and PCs) to manage well, it allows competing PC parties, and it allows Patron play with major wargames etc going concurrently with normal dnd session play.
Variable Time Keeping has no clear advantage on anything that makes a good ttrpg campaign. Some players or DMs may be skittish about running an "always on" campaign, or just not enjoy pondering their hobby as much as JTK players do. But this may be a sign that said players would be better served by a different sort of game.