LOL, well, I can sometimes take between 1-2 hrs for a good complete H&P, so 3 hrs isn't out of the question. At my hospital, I am required to do a complete H&P on all new admits to the general medical floor; this means I literally have to assess all the systems, regardless of what they came in for. Given this, it really depends on several factors, such as the number of comorbities (you'd be astounded at how many concurrent and past medical issues some people have, especially at an inner city hospital) and the ease by which you obtain it (sometimes patients are very poor historians and you have to go scouring through old records and notes to obtain PMH and PSH, which is very time-consuming), how easy it is to obtain their current medications (some patients have an extremely long list, or have no idea what they are taking, so you have to take time to figure it out with them), the number of systems you have to review (at my hospital, I am required to basically ask all of the ROS questions, not just the pertinent ones, so I used to take a long time, until I developed a system to make it more efficient), how complex the social history is, and how cognitively and psychologically with it they are (psychotic, delusional, extremely demented, or obtunded patients can be difficult to assess on a number of levels). It's a learning process. Eventually, you learn how to assess multiple things at once and develop an eye (or ear) for the problematic items and sort of focus in on those things.
The HPI itself generally doesn't take me long to obtain, even with the chatty ones. I think probably, it takes me a few minutes at most. You learn to how to refocus patients when they go off-track and start talking about their dog, the last book they read, the dozen other non-contributory problems they have, or whatever. It takes a lot of practice and patience with yourself, because you have to make the patient feel heard, but at the same time you aren't having a friendly chat, you have a job to do. There's no real how-to advice; just keep at it and be committed to your task without blowing the patient off. Everyone develops their own style and tricks, eventually. It's like walking a puppy. When your puppy goes off-track, gently reel him in and keep at it until you are going the right direction. Over time, you'll find the openings and develop an instinct for what is important. In the meantime, don't be afraid to try different tactics and see what works and what doesn't.
When the patient isn't too complex, I can probably finish the H&P in about 30 minutes, including analyzing all their studies and labs, doing the assessment, plan, and writing orders that need to be written. However, if it's an 85-year-old patient with dementia with psychosis and 20 comorbities (or worse, the completely uncooperative patient or patient who thinks they know exactly what's wrong with them, instead of being cooperative with your interview; those patients probably are the most difficult patients to assess, because they may actively impede you, or try to lead you down the wrong road), and a long social history filled with numerous red-flag items, and a management nightmare due to complicating factors, then it could take up to an hour or more. For me lately, the challenge has been learning how to very quickly put the whole medical picture together based on the H&P, old records, lab work, and other studies, well enough to present the patient in a coherent and concise manner, painting a certain scene based on what they are really here for (which many not be the same thing as their chief complaint).
Anyway, stick with it and keep practicing and learning how to refocus the interview. Avoid being too succinct, however. You might miss what the patient is REALLY here for, or a really critical element (for instance, you don't want to be that guy who misses the fact that your patient is also on Levemir 40-units qhs / Humalog sliding-scale, even though they are DM-2 and on Metformin and Amaryl, or that your patient habitually drinks a fifth of vodka every day).
