"I have seen a bunch of threads discussing the difficulties with accumulating billable hours in patent prosecution. I understand the nature of the work requires intense concentration, and quite a few .1 or .2 hour jobs are done. I still don't quite see why it takes say 12 hours to reach 8 billable"
Sorry if I'm just repeating what others have said... When I was in a firm, it was easy to get pigeon-holed into a very specific technology area. For me, it was hi-tech cellphone prosecution. Not really the "power saving means" or the "new antenna" though I relished even those when I would get them, but more of the alterations of how the phone accomplished error-correction/viterbi algorithm, with applications that would span 50 - 100 pages (and not unnecessarily so). The MEs usually got the less intense cellphone prosecution. All day, almost every day. And I know I'm not the only prosecutor that gets into this type of mind-numbing prosecution. Mostly fixed-fee work. Really intense EE work with little or no break. Occasionally, I would do some legal research on an unrelated area (and loved that, if for no other reason, for the distraction).
For me, patent prosecution each day was like intensly studying for final exams. After about 6-8 hours (with a lunch break some days) I was completly spent. My brain would turn to mush. And, each time I would switch matters, there was some ramp-up time to become acquainted with the application/technology.
With those days where I would do litigation support, and sometimes they would amount to 3-4 days in a row, with legal research and/or document discovery, I could bill 12-14 hour days, efficiently, and go home feeling "fresh". After 6-8 hours of intense prosecution, I was tired/drained. Just my experience as to why prosecution seemed to me to be more difficlut to bill than litigation. I did love the technology and learning about it, but it was just draining.