My wife and I share the same tube of toothpaste. I squeeze from the bottom to the top. That way you use it all. I believe this is the how toothpaste is made. My wife squeezes in the middle of the tube. Her method causes chaos by pushing the toothpaste in two directions. There is paste congestion at both ends.  

Not only do I push from the bottom, I also roll the tube as I use it. This gets it all out. After it's the size of a paperclip, I unroll it, cut it open with a scissor, and scoop out whatever's left. When its all done move on to a new tube. I have carefully explained this methodology. My wife didn’t care. She squeezes all over. No regard for total consumption. The top is caked up with old hard gritty toothpaste. That makes it hard to get it out and its messy. Then she throws it away when its still half full.  What about the environment?  

What about the future? She don’t care. What can be done? I got my own toothpaste and she uses that one too. Now there's two messed up tubes of toothpaste on the bathroom counter top.I’m frustrated and angry. She doesn’t want to hear about it. We may have to get a legal separation of this and maybe all other bathroom products.