I made that mistake when playing FF6. I was like 12 years old when I started playing that game. I wasn't that great at rpg's at that time, so I cheated all the way through (level 99 cheat), and used a walkthrough too! Yet, I still felt like I got a good effect from the story. Apparently, my walkthrough didn't give anything away. Keep in mind that not EVERY walkthrough sucks by giving away the story.
*Spoiler may be up ahead*
On the other hand, I never used any sort of walkthrough on Secret of Mana, and that took me about 1.5 years to complete. Same thing with FF4. I really sucked at that game, but keep in mind that I was 8 years old when I played that game. When I had to board the whale, I couldn't do it. I swear that I pressed every single button possible, and I still couldn't get on. I pressed "A, B, X, then Y, and then R and L" on my snes pad, and I couldn't get on. So, I decided to go off and fight in the underworld. This went on for months, until my sister told me about some dude in her class that had beaten the game. Apparently, I hadn't been standing in the very midde of the vehicle when I tried to board it.
Sometimes walkthroughs are okay to use, but not until you are completely stuck on something.