From talking to a number of other GMs, I'm often struck by just how kinetic a pace they run their campaigns at. PCs usually level from 1 to whatever inside less than a game year. Downtime is really sparse. When I ask them why, and dismiss ADHD as a root cause, this is what I get:
If I allow them much downtime, they'll break my game with their crafting feats/spell abuses/economic schemes/etc. Wealth by level will be thrown all out of balance and I'll have to metagame their future treasure in a way that I feel uncomfortable with (even though the gms in question are less simulationist in bent than I am, albeit still more than the average gm today).
Now when I look at a problem, I ask myself two questions, brought to us by Morden and Comrade Lenin
What do you want? and
Which is to say, what is my objective and who is to be advantaged and disadvantaged relatively speaking over the status quo.
First, what are the objectives.
The first objective is to ensure that adventuring is the highest reward option available to PCs and NPCs of PC caliber. This is necessary to compensate for the very considerable risks involved.
The second objective is to maintain world consistency. The economic model has to be something that the PCs can interact with and employ to some degree. There needs to be an explanation, for instance, for why mid level NPC casters have so much less Wealth by level than PCs in the face of potentially very high spellcasting fees.
The third objective is to ensure that PCs have reasonable downtime options available to them that are unlikely to break the game even in cases like Pendragon where you have maybe one big adventure a year (like an old-school 32 page module), a few minor encounters outside that, and downtime most of the rest of the time, especially in the winter.
On the Who..Whom? question, I want to advantage martials relative to the existing system and somewhat reduce the downtime power of casters.
So this is what I did. It seems to work pretty well in a Core-only environment.
First, I assume that EVERY member of a PC class has an implicit professional/crafting type skill. The number of ranks is Level +3. The controlling attribute is your highest attribute, whatever that might be. That skill might be 'mighty warrior' or 'warrior poet' or 'fire wizard' or whatever. Should you be in downtime, your character can produce an amount of 'value added' equal to
(10+SKILL) * LEVEL /2 per week.
The difference between this and the existing system is the multiplication by level. This system can also be used to replace crafting rules (you finish an item when your value added total plus the materials cost equals the base item value)---at least when the item's DC is something you can take 10 on.
This also replaces magic item crafting rules. Discard all of the item creation feats (lets face it, if your game is using retrain rules, especially ones as liberal as the ultimate campaign ones, PCs can and will retrain rapidly from downtime configuration to fighting trim anyway, so feat investment is no longer a decent argument for effective WBL increase if it ever was in the first place). The leader of the item creation effort makes the roll for success, everyone else participating must have a skill of +10 or better (this is basic masterwork) to contribute value added. For instance:
Volicifar the wizard and his friend Barjin the fighter want to make a magical sword over the winter. Both are level 10 with 24 as their highest attribute. Both have a skill of +20 in their implicit professional skill. Thus each has a value added of 30/2 *10---or 150 gp per week. The sword they're forging and enchanting has a base value of 18000 gp. They start with the ore, magic crystals, etc with a value of 9000 gp (materials cost). So they need to add 9000 in value. This will take them 9000/300 or 30 weeks. If they get their friend Elijah the priest to aid them, they can cut this to 20 weeks---about a winter.
What are they actually doing during this time? Well, Volificar is condensing magical essences and the like and occasionally applying them to the weapon. Elijah is praying a lot...probably 4 hours a day or so. Barjin is instilling the sword with his valor and fame. He's probably using it in downtime while hunting or whacking the occasional marauding orc (all things too minor in CR to shift out of downtime mode).
Suppose the PCs want to make the item faster. Well, they could pay more to hire someone else to do some of the necessary enchanting/instilling work. Basically this is effectively the same as increasing the materials cost. They could cut the time in half by just starting with 13500 gp in materials rather than 9000. Or they could use capital.
What is capital? It is a device, special location, or whatever that allows you a force adder in adding value. In my games I use three categories of capital:
5% capital---this is capital which has neither high risk nor barriers to entry. A great example is a wheat farm in the Dakotas. Capital of this form produces 5% of its value per year in whatever form it is designed to. So if you have, say, a web of shadows that you place to capture essence of shadow each night in the moonlight, that is a good example of magical 5% capital.
10% capital---this is capital that has either high risk OR barriers to entry. BTW, barriers to entry are what Warren Buffet refers to as an 'economic moat'. Such things are the key to actually earning an economic, as opposed to an accounting profit. Say you're a 10th level wizard in a world where such wizards are REALLY rare, like a handful, or are organized into an oligopoly. In such case your essence of fire collector, which requires level 10 to use, would likely be 10% capital. Another example, Mount Doom, if you owned it, could produce as if it were 10% capital because of the risks involved and might have a base value assigned by the GM.
15% capital is capital that has both high risk AND barriers to entry. Example here might be a setup at the Crack of Doom. You need to be pretty high level to use it AND it is pretty risky AND there's only one place like it. Some adventure locations can have as part of their treasure the location itself, as magical capital.
When you do this, the pace of magic item creation slows a LOT.