**The problem isn't that I have to use lots of circumstance bonuses, aid another opportunities, and special options to give my players a reasonable chance of success. The problem is that I have to include ***drastically different amounts* of circumstance bonuses, aid another opportunities, and special options to give my players the *same* target chance of success when the party level, or complexity level, or party size changes. That makes skill challenges very difficult to design.

How do I know that the amount of help I gave that 6-person, level 15, average-skill-modifiers party on their complexity 4 skill challenge to get them a 50% chance of success will also net my new, 3-person, level 1 average-skill-modifiers party a 50% chance of success on their complexity 2 skill challenge? I don't, because it won't. The base system should be mathematically stable so that DMs can easily do all the cool stuff that Keith is doing. But the system just isn't; there's no way to predict how much the help you're giving the players is really going to help them. A DM has to significantly change the amount of help he gives as the party levels, if the party changes size for a session, or whenever he changes complexity. He has to completely re-asses how much help he gives when he gets a new group. A DM just shouldn't have to do all that.

Keith's "partial successes" house rule help with this a little, but not all that much. If the same amount of special options and circumstance bonuses gives one party a 25% chance of success and another party a 65% chance of success because of party size, party level, or some other factor, even when the parties both have perfectly average skills for their levels, that's still a massive disconnect. That first party is going to be getting much weaker partial successes, even though their skill modifiers are no worse than those of the second party. Why? Because the system is fundamentally broken.