In a way, that's what I'm seeing when a GM says that the characters automatically take the Prudence hit.
It seems to imply that the GMs are forcing the characters to move x% into their stake before they're allowed to do anything in Downtime.
As a player, I would resent that. Surely it's up to me whether I want to move money into my stake or whether I need to use all of it to pay for something specific to my character progression.
This strikes me as meta-game thinking and would completely negate the mechanic. Your (ie Arakor's) prudence is what allows you to save your pay check for big ticket items in real life in addition to avoiding the smaller daily over-indulgences of eating in restaurants, buying dvd's of movies that you could Netflix, or starting a Hordes army when your Warmachine one is still in blisters.
Your character's prudence needs to be separately established in order to be effective. It determines whether you buy the inn patrons a first, a third, or a twelfth celebratory round after the adventure and whether you over-tip the waitress. It keeps you from lavishing your new wealth on old friends and relatives as well as any expenses not represented by the purchase of an item or in-game benefit. The player would almost never choose to limit his own long-term buying power thusly but the character certainly might. (Technically, the player does make the choice when setting Lifestyle values.) Consider how many lottery winners bankrupt themselves in just a few years. Likewise, although I couldn't find a clip, the "give us your coins" scene from A Knight's Tale provides a good example.
@Grimace - The system you describe sounds nifty. I can foresee using different values based on location (districts within a city or the capital versus the borderlands) or by circumstance (festival days make inn space scarce, war causes rationing). The Crafty version is less granular which might make it seem a harsher penalty but it is intended to motivate the adventurers to keep adventuring. Alternatively, you could certainly raise the base added to stake value to 50% and reset the increments to 2-3% if it better suits your group.
Hmm, Alex got here first but this is my view.