This. I've yet to see a client development project that made it past step 1 on anything other than the most trivial features. Sucks, but I got paid. What can you do?
I think the advice is intended for products you build for users, not products you build for clients. The right strategy depends on who your customer is. When you find a ripe market, you'll discover that your customers—i.e., the users—just want a solution, even if it isn't pretty. When your customer is the client, then you're selling to him, not to his users, which means you rationally should care less about the product. This can be painful, which is one reason why many startup founders prefer to avoid client work.
If you're good, you can trick the client a bit, deliberately don't completely finish part of 1 till you have most of 2 working.
Don't do this just for your own gratification, but only when it will genuinely help the client.
It helps when you get a sense of how long they expect the project to take - if you do it fast, but deliver a poor solution you are not doing your job.
If they want it fast, and they know it will be poor then fine. But a lot of the time they are not expecting fast, but then you deliver fast and they think "cool", not realizing you didn't really finish things properly.
Alas, the guy writing the checks all too often doesn't see past step 1.