In the area I live, houses are often built one complete room at a time, over many years. They start out as a single-room shack, then the owner builds extensions as they have children or money. Often, they build a porch, and then decades later wall up the porch and turn it into a room of some kind.

I kind of like this analogy because it does help us reason about the situation. The one-room shack is basically an MVP; a hacky result that just does one thing and probably poorly, but it is useful enough to justify its own existence. The giant mansion built from detailed architectural plans seems like a waterfall process for an enterprise application, doesn't it?

There are many advantages to building a house one room at a time. You get something to house you quickly and cheaply. When you build each extension, you have a very good idea of how it will be most useful because you know your needs well. You are more capable of taking advantage of sales (my neighbor collects construction overstock for free/cheap and starts building something once he has enough quantity to do so). It's more "agile". The resulting houses are beautiful in their own bespoke ways. They last a long time, too.

The downsides are that the services and structure are a hodgepodge of eras and necessity. If you're competent, you can avoid problems in your own work, but you may have to build on shoddy "legacy" work. You spend more of your time in a state of construction, and it may be infeasible to undertake a whole-house project like running ethernet to every room.

It's all tradeoffs. I think it does in many cases make sense to build a house in this way, and it likewise makes sense to build software this way. It depends on the situation.

That's interesting, thanks; as you point out, an important aspect of software- as with building architecture is that it tends to evolve over time, and that's where the waterfall approach falls down. However, in software at least, it's not actually necessary to exchange one extreme for another - waterfall or agile; one can take benefits from both approaches, blending foresight and forward planning with modular construction.

> There are many advantages to building a house one room at a time.... It's more "agile"... The downsides are that the services and structure are a hodgepodge of eras and necessity... it may be infeasible to undertake a whole-house project like running ethernet to every room.

The thing is that that end result is actually the opposite of agile, being as it is more difficult to change, and this speaks more broadly to a perennial problem in software development - requirements change regularly, even deep into project development. Planning a design up front does not mean just fixing a specific set of requirements in stone, but also anticipating the things that may change, even without knowing the specifics of what those changes will be, and designing in a flexible way that can accomodate a broad spectrum of possible futures. A car manufacturer might conceivably branch into making other types of vehicles, plant equipment, and similar things like that, whereas they are unlikely to ever get into catering (and if they did, that would likely be a seperate business and a new piece of software). Responding only to the requirements in front of you right now tends to make the design more rigid rather than less, and almost inevitably leads to big balls of mud and big-bang rewrite projects that fail as often as they succeed. Keep in mind also that most software spends most of its life in maintenance mode, so optimising for the delivery stage is short-sighted at best.

Designing software in the way I'm describing is not easy, but it's definitely possible, and in my opinion offers a lot more value than it might first appear.