So I was just watching a YouTube video and the guy on there was doing a outside welding job. He was welding a wheel back onto a shaft. He used 7018 that he said he didn't how dry they were, assuming the rods were on his truck and not in a oven. He took a torch and heated the rods to get rid of moisture. Has anyone ever heard of this or done it themselves? I've never heard of anyone doing it. Just wondering if it would actually work and be helpful.

That will make a junk rod work better. If that's all you have to work with its better than nothing. You are not going to see anything in a code about doing that. It's not a "best practice" . It will make them start easier too.