Defaults matter. Better defaults make you use the tools frequently. The defaults should also consider what is the most frequently used values which can vary per person. So what is a meaningful default for me could be wrong for you. There should be a generic default, the should be an option to override the default manually and there should suggestions while setting the memory defaults.

Also there should be periodic analysis of usage and make suggestions for the defaults. If your system can afford more resources, then you should also have trigger based suggesting. An example would be command x became the most used command by you in the last six months, do you want to set it as your default command??