It all depends on the hiring manager and if the company is willing to take a chance on you. For example, I got hired by a guy looking for a programmer to work on and fix bugs in his autobody shop software.

I had absolutely no professional experience, but I had taught myself Visual Basic. He took a chance on me, took 3 months to train me, and everything worked out for a while. Although I have moved on and gained a lot of experience since then, it was at his sole discretion to take that chance on me.

I would think if you have some knowledge in something, they could take a few months to get you up to speed. Most companies don't hire you expecting you to know everything immediately. So some training, and if after than, you just "don't get it", than they know they made a mistake. But if you spend a month or two in training... it is likely they will get you up to speed and you will get it.