Remember setup costs.
If it takes one hour to set up a new computer–install all the software, set up the email client, update the antivirus software–how long does it take to set up 5 computers?
Should take 5 hours, plus a small amount of switching cost. Right?
Not even close.
How long did it take to decide on the list of tasks that had to be completed on each computer? How many meetings, phone calls, and email conversations had to take place? The time to research what hardware to buy, what software, what versions, and a reasonable price? To get budgetary clearance? To get the hardware delivered, then unboxed?
What about the time it took you to get comfortable with the new Windows installation process? What about the software driver that was incompatible with that version of Windows and the time it took you to find an obscure website with a driver that worked? The number of times the installation was 99% complete before it crashed completely, leaving you to start from scratch until you found a fix for the bug that was causing the problem?
What about the time to test the system to make sure everything worked? The time it took you to write the tests? The time it took you to interpret the results of the tests?
Do you get it?
A car that is traveling at 60 miles per hour will take 1 minute to travel 1/60th of a mile.
Walking to that same car, putting on your seatbelt, starting the car, adjusting the mirrors, then accelerating to 60 miles per hour, then slowing down and stopping at the end of the 1/60th of a mile will take considerably longer.
Now consider that the driver also has to study for and pass a learner’s permit test, find a driving school, learn to drive, pass a road test, get insurance, research vehicles, qualify for financing, and buy a car.
You have to consider the time you spend learning and setting up your task or process or outcome as part of the whole process. It’s not always going to be so dramatic–maybe you already have a car, or are an expert at installing Windows–but there will be some setup cost.
No project starts at full-speed.