(excerpts from The Pipeline: Picture of Homebuilding Production©)

“Managing a production system requires concentration”, said the intrepid, results-based consultant.  “It requires focus.  Focus requires prioritization of tasks.

“If a task is the most important, critical step in a process – the pacemaker, the constraint, the bottleneck, the task that determines the throughput of the entire system – then you cannot divert attention to a task that is not as critical.  Even if it is not the system constraint, multi-tasking without focus and priorities is counter-productive.”

She drew two simple charts.

“Look at the first chart”, she said.  “You have four projects in-process, which you choose to work on at the same time.  You do them concurrently.  You multi-task them.  The tasks on each project requires one week to complete.  When will the first project be completed?”


“Week 4”, said the VP of Sales.  “For that matter, all of the projects will finish in Week 4.”

“So – does multi-tasking meet the requirements of homebuilding?  Does this look like the way we want to schedule jobs?  Is this even-flow?”, she asked.  “Let’s look at the alternative, which is to complete a project – in its entirety, all of its tasks – before moving on to the next project.

“Look at the second chart.  Same deal, but you do the projects in sequence.  You complete them one-at-a-time.  You don’t multi-task.  In this case, when will the first project be completed?”

“End of Week 1”, replied the VP of Sales.

“In the first table, when does the first throughput occur?”, she asked.

“Early in Week 4”, said a superintendent.

“In the second table, when does the first throughput occur?”, she continued.

“End of Week 1”, he said.

“All of this work is being performed by the same resource”, she said,  “Now, look at when the next resource gets to work on a project.  In the first table, the second resource gets all of the projects completed by the first resource essentially at the same time, at different points during Week 4.  In the second table, the second resource gets Project 1 at the end of the first week.

“It’s the same amount of work.  In either case, the first resource should finish all four projects by the end of Week 4, so we get the same amount of throughput from it during the entire four-week period.

“But – we get the throughput much faster when it does not multi-task its projects.

“Which system requires the most capacity?”, asked the intrepid, results-based consultant, pointing to the two diagrams depicting the effect of multitasking.  “Which system carries the most work-in-process?  Which system has the most complexity?  Which system costs more?”

“The one that kills more of my brain cells”, answered one superintendent.

“It’s an illustration of the finite capacity and variability buffering we have been talking about”, she said, ignoring him.  “If you fix the amount of capacity and increase the amount of inventory, yet do nothing about variation and uncertainty, the system has no choice but to lengthen cycle time.  That’s the undesirable effect of multi-tasking.

“But, multi-tasking is not the only behavioral tendency that causes the long durations that we are concerned with”, she continued.  “We pad duration to create safety, but then we waste all that safety, by waiting until the last moment, by letting the work expand to the allowed time, and – yes – by working on multiple jobs at the same time.”

“That might be the case in ‘real’ project management, but not on my jobs”, argued another superintendent, one of the younger ones.  “My framers have full crews on each job.  Same with the electricians, plumbers, masons, and everyone else.”

“Bulls–t”, said the VP of Construction.

“I can’t tell you how many times your framer leaves three guys on your job and sends the rest of the crew to get another job started”, he said.  “It happens all the time.  It happened to you last week.  The truss package showed up a week late on Lot 40.  The same day, the trusses showed up on Lot 47 three days early.

“Two jobs with trusses on the ground, and one framing crew to fly them.  Where’s the crane?  On Lot 47.  Which job is behind schedule?  Lot 40.  So, why don’t we send the crane to Lot 40?  Because we can’t.  Lot 40 has a purchase order issued to another crane operator.

“A lot of times, it’s not even their fault.  We tell them to do something, because we can’t seem to get our own act together on resolving the resource conflicts between open jobs.

“But – it’s not one behavior.  It’s all of it – the multi-tasking, the waiting until the last minute, the pacing of work to consume the allotted time.  There is variation in all its forms.  Different outputs from repeated applications.  There is risk and uncertainty.  Things that are indefinite, indeterminate, and unknown.  Weather.  Delays.  Mistakes.  Failed inspections.

“Things that go wrong.  Murphy.

“And – we step right into it.

“If you can’t see this, then you will have to come up with a different explanation – a different excuse – for why your jobs average 180 days, when the schedule itself specifies 120 days, and everyone acknowledges that it should only take 90 days.”


(The Pipeline: A Picture of Homebuilding Production© is available from the publisher website (virtualbookworm.com), as well as from amazon.com, barnesandnoble.com, and booksamillion.com;  usually in-stock on amazon.com)