Yes, it is true, but many of us begin to build our lab and when we finish one target we already know the weakness, password, etc, etc, and you are tired to build something and now brake it.
Because we feel the same pain we created our Online Penetration Testing Lab or Ethical Hacking Pentest Lab online, in this place you can attack all you want, these are private targets with vulnerabilities and bad configuration.
We make it simple, just turn your attacker virtual machine, run OpenVPN and begin to attack, in 5 minutes you are running exploits, Metasploit, check web applications weakness, etc.
So now you focus in develop your attack techniques (you already know how to build servers and network).
Develop your attack techniques?Yes, in the beginning your run all kind of exploits, then you try to run only the right ones, and the last one is you try to make it perfect and avoid to be discover, to do that you need to practice more, and a little more and just more.
So focus learning how to attack and how to protect your customers networks. Hack is fun.