Agile vs Waterfall: Waterfall Wins! + CHEAT SHEET

Episode 40 - 15 Jun 2016

In the previous episode my 19 year old self took on my dad in the classic DIY challenge of hanging a shelf.

  • My process was Waterfall
  • My dad's process was Agile

My dad's Agile process won by a landslide.

But why did it win?

And are there cases where Waterfall would be victorious?

Enjoy the video!

Remember to grab your FREE Waterfall vs Agile


My 19 year old self took on my dad at the classic DIY challenge of hanging a shelf.

To no one's surprise, my dad won.

It was not just a victory of experience over enthusiasm. It was also a victory of Agile over Waterfall.

Was Waterfall destined to lose? Or could it have claimed victory?

What has to be true for Waterfall to win?


If you missed the last episode...

... you may decide that you were glad that you missed it.

Because we spent the entire time attaching this shelf...

... to this wall.

Not once...

but twice.

My method of hanging the shelf - very much a Waterfall approach - scored high on efficiency:

  • I measured everything
  • marked everything
  • drilled everything
  • screwed in all the screws

But it scored badly in effectiveness: the result was a wonky shelf.

My dad's process was was much more iterative - much more Agile.

  • He marked one hole
  • He drilled ONE hole
  • He fitted one plug
  • He fitted one screw [And so on...]

He checked for level multiple times, so it came as no surprise that the end result was also level.

It was a fair fight: my dad's method won fair and square.

But it did make wonder: why did it win?

And could there be situations where a Waterfall approach would be victorious?

Let's change the parameters a bit: instead of the challenge being to hang a shelf, the challenge now is to hang 20 identical shelves.

My dad's process is awesome for a single shelf, but for 20 shelves it's far too much work.

His process is bespoke.

I need something more "cookie cutter".

I've come up with this jig; I think it's going too make all the difference.

Match this mark to the centre mark on the wall

Adjust for level... using the built in spirit level.

Press it firmly against the wall: the rubber backing keeps it in place.

The drill guides ensure that the holes are in exactly the right location.

It also ensures that the hole is drilled at right angles to the wall.

Drill all 4 holes.

Remove the jig

4 plugs in

Offer up the shelf

In go the screws - but not too tight.

Final check for level.

Tighten the screws all the way.

Not just a job done well.

But a job done quickly.

Waterfall just beat Agile.

Why did Waterfall win?

Clearly, the jig was the enabler here.

But in order for the jig to work as expected,

at least two things must be true:

  1. All of the walls must be reasonably flat

if they're not, then the jig won't "stick" to the wall.

  1. All of the shelves are identical

if they're not, the holes drilled in the wall won't line up with the holes on the shelf.

Notice that neither of these conditions is necessary for my dad's process to work:

his process will always work: on flat walls; on bumpy walls; with shelves of all shapes and sizes.

So it would appear that it's all about predictability.

If the steps can be predicted with a high level of confidence

  • for example, if it's an activity that we've completed many times before -

then a Waterfall process is likely to be the best choice.

Conversely, if the level of confidence is low

  • for example, if we're attempting something for the first time -

then an Agile process is going to pay dividends.

Agile and Waterfall. Horses for courses.

Many thanks for watching. Talk to you next time.