These aren't actually conflicting opinions. What you need and are trying to accomplish is strength training and muscle growth. The way strength training works is, you work the muscle(s) to be trained until micro-tears develop. Then when the body is putting the muscle back together, it reinforces the damaged area, making the muscle just slightly larger and stronger than it was before. Do this repeatedly, and you can become much stronger than you were before.

But you have to remember that you are deliberately injuring yourself. "No pain, no gain" isn't just words. You can only push an already-injured body part so far before it fails altogether, and you wind up with something major. Try to keep it down to the level of microtrauma, don't go until some connective tissue rips away. You need rest time to heal and rebuild in between the times that you're pushing yourself.

When I'm deliberately pushing a body part that hasn't seen much use lately, I like to start off going as hard as I can as long as I can for 2 days, then taking 3 days off before I start again. I do that until the pain goes from that acute "Oh God I'm dying" feeling to the quieter delayed soreness that just says it's working, then bring it up to 3 days on and 2 days off. I stick to that until it feels good, usually a couple weeks, then shift to 5 days on and 2 days off -- work all week and have the weekend to recuperate. It works for me.

I don't know what your diet is like, but remember one thing: You must eat sufficient protein after strength training. I don't care if you're a vegan, figure something out. Your body needs the raw materials to repair damage to your muscles and build in reinforcements.