thought I'd join in the conversation though I'm far from the most prolific producer here...
my first year in AD I came out with 2 hrs of programmng, 1.5 hrs the next year, and .5 hours this year
the irony is that the post-production time on my latest show was far less than the others, because it was entirely recorded in the field so I didn't need to do a lot of post-pro work like adding footsteps, clinking glasses, seagull sounds, etc...
the flip side of that is that my standards have grown exponentially, I was working with a much larger cast, and I really wanted to nurture this story and not rush it out like I have with shows in the past.
so I don't have a formula for how long it took, but I wrote the script originally in November 06, rewrote it twice this winter, and revised it extensively up until casting it in June... yet, after ~ 4 hours of recording time the production part was done!! and about a month of off-and-on post-production.
what I'm getting at is, your mileage will vary ;-) as I think everyone's already talking about, you can sink an infinite number of hours in a story if you want, and if you make a few right choices in pre-production it'll save you dozens of hours later on. and we all have different goals/capacities when it comes to producing. I have sooooo much going on in my normal life that I feel pretty proud that I got ANY thing out this year!