In 2007, Weebly co-founders Dan Veltri, David Rusenko and Chris Fanini were looking to grow their three-person team.

"We were hiring our first person. We knew it was a critical hire and we couldn't make up our minds," Rusenko, CEO of the web publishing start-up, tells CNBC. "So we thought, well why don't we bring them in for a week and work with them? We'll pay them and just see whether it works."