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“Mystery of Lost Time” – or – How to Create the 25th Hour / 13th Month?

Meet the author:

Tal Levanon – Founder and partner in “Tal Levanon – HCP Ltd”, an expert project scheduling consultant and creator of the Hidden Critical Paths (HCP).


What would you give for another hour in the day? To sleep, to finish getting ready for an exam, or maybe just to have another hour of fun?
In reality, probably no one has found a way of doing this (and if someone has – than they are keeping it top secret); however, in schedule software – some have found a way, either inadvertently or purposefully😊 …

HCP app | “Mystery of Lost Time” – or – How to Create the 25th Hour / 13th Month?

Schedule: how to create the missing time?

First, a word of caution: this is a very technical post with lots of details! Not for the faint hearted😉 …
Clarification: the data is taken from the Project software. It is principally the same in Primavera, though accessed differently.

Every software has a calendar setting. The calendar allows configuration of workdays and vacation days, and of work hours. The default setting for a workday is the American workday:
8:00 am – 12:00 pm, 4 hours of work.
12:00 pm – 1:00 pm – lunch break.
1:00 pm – 5:00 pm – 4 hours of work.

Meaning: the workday has 9 hours, 8 of which are work hours.

HCP app | “Mystery of Lost Time” – or – How to Create the 25th Hour / 13th Month?

Find it in Project: in the Project menu, select “Change Work Times”.

Most of us look at this and think “No way. We work from 7:00 am to 7:00 pm non-stop!” Furthermore, we also work Fridays… The schedule is revised, and the problem is solved.
But is it though?

Well, not really. There is another setting accessible by clicking “Options”. It is the basic definition of the basic data and, in some way, it “supersedes” the calendar settings.

HCP app | “Mystery of Lost Time” – or – How to Create the 25th Hour / 13th Month?
No one will reveal new details about your schedule?
Hmmm… 🤔

If you want to test that, try HCP-Go

HCP app | “Mystery of Lost Time” – or – How to Create the 25th Hour / 13th Month?

This setting configures the following:
Default time for day start, the default setting is 8:00 am.
Default time for day end, the default setting is 5:00 pm.
No. of set work hours per day, the default setting is 8 hours.
No. of set work hours per week, the default setting is 40 hours (8 hours/day * 5 days/week).
No. of workdays per month, the default is 20 days.

Meaning, whoever changes the schedule hours must also change these settings. For instance, if we decide to work from 7:00 am to 7:00 pm on weekdays and from 7:00 am to 1:00 pm on Fridays, the default hour for day start needs to be changed to 7:00 am, the default hour for day end needs to be changed to 7:00 pm, work hours per day will be set to 12, hours per week will be 6 (Friday) + 5*12=66, and it is best to also set 22 workdays/month (more appropriate for calendar months).

Schedule management: is this “trick” recommended?

If your project is scheduled by hours, all of your activities are scheduled by hours. If you truly have no break time (not even at 10:00 or at lunch, or for dinner…) then this trick is highly recommended! However… If your project is scheduled by days, and not by hours, then it is really not recommended.

What happens when someone changes the calendar but not the default settings? They invent missing time 😊! How? Well –
If a certain activity is set to last 4 days, this is how the scheduling software will operate:
A workday is 8 hours, by default, meaning 4 days = 8*4 = 32 work hours.
If an activity starts Sunday morning, we will have 12 work hours on Sunday, 12 on Monday and another 8 hours on Tuesday, and we will complete the task at 3:00 pm! Excellent! A task that should have lasted 4 days ended within less than three days in the scheduling software! Now you can start Thursday’s assignment on Tuesday! Fantastic! This is how we cut project length by a third! (Every 3 workdays become 2 workdays in the calendar – in the software!)
Real? No.
Possible in the software? Yes.
How can we find it? The easy scenario – where there is no general compatibility between the calendar and default settings – you can check independently. But in special cases, it is difficult to do a manual check. However, you can easily check all cases using the HCP – Hidden Critical Paths app.

To activate the free app on your schedule, click here.

For more information, click here: ‘Knowledge Center’, section 2.5, ‘Incompatibility Between Settings of Activity Times and the Schedule’.

Schedule management: what should we do?

  1. Add holidays to the calendar. All of them. If you are affected by various religious holidays – set them as “no-work days” in your calendar. The reality will remain unchanged. We do not need to “fool” ourselves that these are workdays, when they are not.
  2. Fridays – don’t set them as workdays. Why? There will be a separate dedicated post on that.
  3. If your project is scheduled by days and not by hours – the answer is simple – don’t touch the hour settings.
    For your information – the software schedules the activities by minutes (not by hours…) but presents it to us in a comfortable layout.
  4. If you are required to schedule months, you should change the default setting from 20 days/month to 22 days/month (where Fridays are not workdays). 22 workdays/month are not exactly a full calendar month, but mostly, they are a better approximation of a calendar month than 20 workdays.
  5. The guidelines in sections 1-4 above should be handled before building the project, otherwise – if you had already begun building the project and then change the calendar settings – you need to carefully check that you have no errors, e.g., an unintentional shorter or longer duration of activities…

And as for the 25th hour or 13th month – there is an excellent book: “The Girl, the Gold Watch & Everything” by John D. MacDonald, published by Fawcett Gold Medal, 1962.

This Post Has 2 Comments

  1. Hello hcp-consulting.com owner, Your posts are always well-structured and logical.

    1. Thank you!

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