Do practice permit tests really help?

I need to get my permit but I am too afraid I'm gonna fail even though I've read the Driver's Manual. I've taken a ton of permit practice tests and my scores have been really hit and miss. So I was just wondering if what they ask on the practice tests is also on the real one.|||make sure you know all the roadsigns. my test material was 100% from the manual, so I would read the book thoroughly.