As far as I can discover the use of the term “Conrad” to designate 800 words of writing at a sitting is private to Will Self — but, who knows, maybe his chums all talk in such units. Maybe they say a “Delderfield” to indicate the pinnacle of 10,000 allegedly reached daily by long-distance writer R. L. Delderfield, or a “London” for the 1,000 Jack London’s said to have generated daily. (Though this chart credits him with 1,500.)* On the street the word (apart of course from designating The Secret Agent‘s creator) appears to mean some kind of cool dude. Mr Self — can he really be content to be described as scabrous — is quoted at TeleRead as attributing regular morning Conrads for his success as a writer. He can dash off 500 words an hour in his journalism (and I’ve noted some over-hasty journalistic writing of his) but when working on a novel can only do 1.25 Conrads (i.e. a London) in a morning, which maybe we can assume to be four hours, and thus half his unbridled rate.
I dare say the rate is less important than the regularity. The more you can make your writing a regular process the less likely you are to succumb to distractions such as writer’s block. If you only write when you’re inspired — well, you have to sit around until inspiration descends upon you.
* I admit that the differences between the various sources merely indicates the stupidity of trying to measure such an obviously unmeasurable quantity; a quantity whose inherently variable value has in fact invariably no inherent value.