This is a good solution if you simply want to keep up with Ruby's development or you usually work with one version at a time, but not for projects where you mix

This is a good solution if you simply want to keep up with Ruby's development or you usually work with one version at a time, but not for projects where you mix and match. For instance, at my work we use multiple Rubies, including jruby, and a tool such as rvm is a must in this case.