I was getting through 500 a day, but I have reduced it to 250 on more days now. This is because, unlike me, the cardbox has a limitless capacity for gobbling up what I feed it. I am giving it not only the words I miss (known but not got and never seen before in my life) but also ones that were guessable, just to reinforce them in my memory.
My hit rate varies between 70-90% on the 'new' words, and I am about 90% on the cardbox. It does seem to take 3 or more goes at getting some of them fixed in my brain. And some I totally despair of ever getting right on a consistent basis.
It is nice, however, to be doing something new rather than keep going over the same stuff . There are some really neat words that I may never get to play :)
I hit the 35000 mark yesterday...