On a slight tangent, I have a sister-in-law who made partner at a NYC law firm -- part time (she almost made it at a different one earlier but wound up moving out West for a while. She says she is Highly Desirable to clients because she's actually polite to them, even on the phone, which is apparently enough to really differentiate a lawyer in NYC. But that I learned recently, and other than passing it along as An Important Datum, I'm not sure what use it will ever serve me. It might help you or someone you know tho so don't hesitate to pass it along.
Returning to the ability-to-estimate question, despite knowing in principle the importance of this, it took me a few years to get a handle on Actually Doing It, so I've committed my own share of Hideously Aggressive Estimates. By the time I got to Amazon, however, I had a system worked out, and it basically amounted to this. Break the work down into recognizable bits. Estimate each bit, assuming you get to work on it 4 days a week, 2-3 hours a day (because with the level of interruptions I suffered, that was optimistic). Request time estimates from anyone else involved, and add comparable amounts of padding. Then build into the entire schedule the Sick and Vacation estimate (this is a seasonally adjusted percentage of days lost to sick days and vacation days, that can incorporate actual plans if known, but is otherwise produced as a Wild Assed Guess). This is different from putting together a full-time-on-project estimate and then padding by n percent -- the numbers can vary wildly, and if you have a real handle on how much time you have during the week to do Real Work On This Project and your Sick/Vacation guess is good, you can really nail the due date pretty consistently. It's really fun to do this to other people (take their estimate and hand back what you really think it will take -- and be right).
I'm sure that scheduling appointments like in a health care providers office is different. There's a longish thread over at the Well on the NYT where a lot of bitching about doctor's are always late is going on, and the doctors say well there are emergencies and people who've been around the block a few times point out that those emergencies happen with _stunning_ regularity. So I'm going to take a little stab at How to Schedule Appointments to Minimize Being Late for Clients (because I don't like the term patient. It implies we should be. And as Mr. A. said, patience is one of the Lesser Virtues).
(1) Based on how late you are running each day (or how early you have to stack the pre-start-of-day-appointments), schedule enough open appointments to return you to a reasonable length day (you define). If by some miracle, there is no one who needs that same-day slot, or who spills over into that slot, or whatever, you can use that time for coffee, a meal, charting, etc. If you were already building in some number of slots and still spilling over, build in more.
Just to indicate that I have a clue how this works, there were days at Amazon that I brought a magazine. I couldn't get enough time to read e-mail and respond, so I'd sit and read a paragraph or two of an article in a magazine until the next person showed up at my door who Had To Talk to Me Right Now Because It Was SOOOOOO Important. Maybe you shouldn't schedule _any_ appointments in advance. Especially for the first week after school starts (if you see children). Or during flu season. Or whenever the really-busy-time is for you.
(2) Refer patients to another provider. Aggressively. If you're that busy, you aren't helping them. Help them find someone else who can. Elsewhere, we call this delegation. If you're doing a bang up job as a health care provider, you should think of yourself as requiring a team of people to replace what you have been doing; start finding that team and handing work off to them. Now.
(3) _In addition to_ scheduling open appointments, stagger less-than-appointment length blank periods between _every single appointment_. So if you have 15 minute appointments, don't schedule more often than 15 minutes + n. That way, if someone runs over, you've at least got n. If you genuinely cannot help people in the time slot that you've been assigning, expand the slot and then pad. If you cannot do this and stay in business, that's a strong clue to find another business. If you think you can help your client in that time slot, but your clients differ with you, see #2.
(4) Once you have this system up and running, you should see the following pattern: you are waiting for the beginning of the next set appointment as often as you are late to the next set appointment. The distribution and details will vary, but the goal is to find the middle. Once you've got that nailed down, start training your patients to arrive 10-30 minutes early, so they can _fill in the blank spots_. Good practices do this. I've shown up early and gotten someone else's slot because they weren't early enough for it -- or they were late. Either way, I benefited, efficiency benefited, etc.
(5) Stop taking new clients when you hit a point where serving your existing population is taking up almost all of your time. Be really serious about this. See #2.
There are almost certainly practices and specialties and locations where this set of rules is doomed. (ETA: Docs who take free patients who qualify, for example, are probably going to burn right through all these rules for economic reasons.) Rural areas with inadequate service is an obvious one. There's one really common scenario, however, that does _not_ excuse failure to adhere to this set of rules: your clients want to come in almost exclusively in the mornings before school/work, in the afternoon or evenings after school/work, on Fridays, or on the weekend. A lot of practices as a result are zombieville during the daytime (I _love_ this and I have for years) and madhouses during those hours on the edge. Further, they run late a lot, due to traffic, child care snafus, unexpected meetings at work, blah, blah, blah. Probably a lot of no shows, too (altho with the number of people claiming 20-25%+ no shows, I gotta wonder what the hell is going on). It seems to me that you probably should just close up shop and treat the whole thing as shift work. Clearly, you wouldn't lack for clients.
Obviously, this stuff can only be implemented at the business level (and solo practices are a bygone operation, so it's probably not the health care provider's decision). But it _can_ be implemented at the business level -- I've been to practices that consistently worked this way. Of course, they also are heavy on the nurse-practitioner/physician's assistant/non-MD staff. Maybe that's the real key.
ETA: And what _is it_ with people and eye contact? There's this whole other subthread about people demanding eye-contact or being upset when eye-contact is demanded. I thought this was a well-understood difference -- some cultures do, some don't, it's usually a power thing, and of course there's the whole ASD issue.