Sorry to rain on your parade (itchy):
Ok I vote the q 3-4 calls really stink and if you have family forget it you'll never see them you will be pre post or on call. Although 18 weeks of nights split between 3 months (I agree with pruritis_ani (see I actually do agree with you sometimes!)) stinks. Night float does a toll on you-- but the trade off is that you have no call on the week days HAVE A NORMAL SCHEDULE and actually can get off 1 or 2 weekends a month as an intern more as an upper level.
As far as 1 in 7 call I am not sure if any programs do that.
At most night float institutions calls are Fridays/ Sunday (Sunday until 6pm then night float takes over) or all day Saturday 7am-8am Sunday.
Actually, all of our interns get at least one and typically two weekends off per month...without night float. Q 3-4 call is not a picnic, for sure, but it lasts exactly one year. Really only the first 2 months here, then it is more q 4-5. As an upper year it is q 4-6, with q 5-6 being by far the more frequent. As a chief, you are home. Call me crazy, but q 5-6 equals 5 or so calls a month, with maybe one being a weekend. That is a piece of cake, especially since there is no "post call" problem. You go home, take a nap, have the rest of the day free and then get to bed after some family time!
As for the family situation...well, leaving for work at 530pm (when my family gets home and ready for dinner), then coming home at 730am (when my family is going to work) really sucked.
Our hours with night call....rounds at 0600-0630, clinic from 0900-1700, busywork til about 1800, latest. If you are on the floor, you sign out at about 1730. If you are on call, it is 24 hours, followed by 24 hours off. Weekends only if you were on call, which was about once a month.
With night float:
Night float 1730-0730 Sun-Thur
(Night float stays friday for didactics until 1200)
Non night float: Rounds 0630, clinic 0900-1700, busywork til 1800 latest (same as night call)
Rotate weekends...which puts you on at least 2 weekends every month, unless you are on night float.
Your program may have a different night float system, but here those of us with families unanimously hated it, as we could not see our families, and our weekends off sucked because of your sleep cycle.
Again, night floats are not all created equal. And, the nonsense about spending more time with the family is just that...nonsense. My family time is after work and on weekends, and these are the exact hours that night float systems take away from you.
Don't be scared to stay the night in the hospital once in a while if it gives you many more days when you don't have to even come into the hospital.
The point of this lengthy post is to really make sure people look into the reality of the individual schedules, and not say something silly like "night float is better". Night float systems are almost never less hours, they are simply distributed differently. If you have a lot of residents, and don't lose all of your free weekends, it may be a better system. But, night call is not evil, and in many cases it actually is a LOT better in terms of free time away from the hospital. Almost to a person, the people I have worked with and spoken that have done both systems prefer the night call system. There are a few that like the night float as well (funny, though, in my program it is the single residents who want to go out and don't have family to think about). Just truly make up your own mind on a schedule by schedule basis after deciding what time is important for you to have free. It is a mistake to classify programs simply as "night float or regular call", and you may wind up misunderstanding a great schedule.