Powdork - 7:36 am on Oct 6, 2005 (gmt 0)
It depends on what is currently limiting your spend. Is it because you are bumping up against your daily or monthly budgets? Or is it because you are getting as much traffic as you can at current cpc? If it is the former, you may be able to extrapolate until you reach the latter. I say 'may', because it doesn't matter unless your additional traffic places no noticeable pressure on the advertisers budgets. In terms of clicks, it is easier for me to pause or adjust all my Adwords campaigns than it is for me to view stats from two days ago in adsense. If I notice the money flowing out too fast (and I check those stats religiously too) I make an adjustment immediately and many times its a full stop.
Which is also the reason that jumps in traffic or search engine rankings don't always bring the windfall one would expect. Google makes it very easy for us to limit our advertising spend and it definitely has an aggregate effect.