Close, but it doesn't look like anyone has the whole cigar.
The reason you are limited to 12 hours in Package (besides making it easier for them to keep accounting of your hours) is 395.1 (e), the short haul exemption. The DIAD is not an approved on board recording device so we would not qualify for the exemption. Once you go "on road" you are considered Driving for DOT purposes until you go on break (on duty, not driving) or meal (off duty). (Technically, break would be considered "off duty" but UPS does not agree of course. The deciding factor is if you are 'released from duty' for that period, not if you are being paid, but it doesn't really matter.) The record keeping requirement is in 395.8
Driver's record of duty status. - Federal Motor Carrier Safety Administration
But wait! 395.1(2)
exempts non-CDL required Drivers from 395.1 (e) if:
(i) The driver operates a property-carrying commercial motor vehicle for which a commercial driver's license is not required under part 383 of this subchapter;(ii) The driver operates within a 150 air-mile radius of the location where the driver reports to and is released from work, i.e., the normal work reporting location;(iii) The driver returns to the normal work reporting location at the end of each duty tour;(iv) The driver does not driveA) After the 14th hour after coming on duty on 5 days of any period of 7 consecutive days; and(B) After the 16th hour after coming on duty on 2 days of any period of 7 consecutive days;(v) The motor carrier that employs the driver maintains and retains for a period of 6 months accurate and true time records showingA) The time the driver reports for duty each day;(B) The total number of hours the driver is on duty each day;(C) The time the driver is released from duty each day;(D) The total time for the preceding 7 days in accordance with § 395.8(j)(2) for drivers used for the first time or intermittently.
Clear as mud isn't it? Keeping to the 12 hours is probably best for everyone concerned as it pretty much keeps everyone in line with the requirements.
The 100/150 air mile radius is also an important factor. You probably have shuttle runs in the outlying centers that come close to violating this radius (and I bet quite a few do). It's shorter than you think when you see it mapped out.
Also in 395.1 (b) is the adverse driving conditions exception.
See the interpretations for more information: Interpretation for 395.1: - Federal Motor Carrier Safety Administration
UPS only publishes the Summary that was already linked, as it mostly covers what they want you to do.
Summary of Hours-of-Service (HOS) Regulations - Federal Motor Carrier Safety Administration
Also in dispute is the 60/70 hour 7/8 day clock as UPS likes to keep you on the 60/7 when not working Sleeper. You can do either, which is why you see a Contract proposal to compel UPS to use the 70 hr clock during Peak.
You are not required to "reset" in 34 hours, you can just keep rolling. In Package or Feeder working days you will eventually run out of hours for a day and have to sit out until one drops off. If you work nights, say 1800-600, the first 6 hours (assuming no meal) would drop off later in the week and you could still work picking up more hours after midnight again. To keep rolling you cannot work 12-14 hour days or eventually you will run out. Work 8-10 hours give or take and you can keep rolling almost indefinitely if your start times work out. I have a good Excel spreadsheet for 60/7 if anyone needs it. It works on smart phones that can run Excel too.
Keep in mind that a lot of these rules will be changing come July if the Final Rule is implemented on schedule. ATA is suing to prevent this but I haven't kept up to date on the progress. Generally it's tough to stop a rule before it's implemented as long as they went through the process (and boy did they).
Also, while you
cannot drive on road after your 14th hour, you are free to shift or work in the hub as long as you wish, provided you have 10 hours off before the next time you drive and don't violate the 60/70 hour limit. I used to have a run where I would hit my 60 on Thursday then pick up an extra 2 hours or more building sets in the yard. Those were some fat paychecks!