Comment by creer

The very specific example you chose: payroll, shows how it can be difficult to incrementally step from small to huge. As you grow from town to national, you will run into all the disadvantages without really hitting the advantages. I feel that incremental does help you move from one level to one just a few above. But only if there are enough customers at these starting levels exactly.

When developing for towns, you will have all small random subsets of the variations imposed by year after year of legal changes BUT small sales. You will have to implement niche variations in arbitrary aspects for all the towns you have to support AND you will not have the customer size on which to amortize this work. Each new customer will bring a new arbitrary set of legal aspects to be met. Each new customer may be arbitrarily difficult to support.

By the time you reach national, you will have already covered most of the historical legal quirks - but that will have been done in one kludgy manner after another - and then you will hit one more set of legal quirks at the level of national organizations (some of them will have their very own laws). You will now have a very large budget to finalize things but you will be burdened by an illogical software base.

So I agree that you will need experience and subject matter experts that have worked at the various levels. BUT, now that you have this experience you now know the degree of flexibility that is required (you know where and what needs to be variable and quirk-friendly and how far the quirks can go = "any size") as well as size-related issues (mailing, transaction, user support volume) and you can now plan for all this AS YOU restart a new development from scratch. Because at this new "master" level you need both systematic flexibility AND relience at size.

Payroll is exactly the kind of topic where "adding features" will be "fun" - I mean bewildering - while you learn, but probably economically difficult to manage, until it kills you "as you climb up"?

You will be killed by a large software project that can afford to hire out a bunch of your subject matter specialists (or hires new ones) and uses them in a "from scratch" project. If you are lucky, this large project will be from the same company but only if you are lucky.

Now. AFTER you have done the one top level project - for one country -, you will probably be in a good situation to sell service to all kinds of organizations. Because you now have a system in which you can implement ridiculous quirks without breaking everything. And if you have done the job just right, you can onboard smaller customers (towns) economically enough that they can afford your solution.

That's different from where you deploy your solution first. Sure, deploy a national-design solution first at a subset of the target employees - although that does impose more requirements still: now you need to coexist with the legacy solutions. Which would be another hard to meet handicap when developing for towns first.