Do you spend an awful amount of time building your landing page/app?

Generally, when I come up with an idea for a service or product, I dive right in to making the landing page and sometimes even the app. But what happens is that I don't have enough motivation to continue on the idea after a week or so and then it just gets sent to the idea morgue.

I know that the best way to get motivated is to actually talk to users and find out if they have the same problem that I've identified.

But I often find that to get some serious validation (intent to buy/use) is to actually have a landing page and see if my target audience actually resonate with the problem.

What do you fine folk do? Do you find yourself going through the same phases?