papers: 5-2 years
slides: 2 years-cutting edge
a few blogs are about as good as slides (basically when they're serving the same purpose: technical communication with peers)
YMMV, but I aim for things that people spent a long time thinking about to prepare, in order that I may learn from them in a much shorter time:
Good books probably take 4-12 months (wall clock) to prepare, but I can digest them in days to weeks. (theoretical CS and maths take longer to digest; I'm guessing they're proportionally more difficult to write. a physics anecdote: Halliday and Resnick reportedly took 5 years to prepare their 1st edition.)
I'm not sure I've run into anyone who's consistently written more than 6 good papers a year, so call them 1-2 months to prepare; digestible in 1-2 days.
Slides or the better blogs may take days to prepare, yet are digestible in fractions of an hour.