Preventing Visual Studio from removing "using System"

Here is the best alternative:

• Critically look at your project's references and remove everything you do not use as soon as possible;
• Always use VS's Organize Usings -> Remove Unused Usings as soon as possible;
• Never be afraid if some using clause you planned to use has gone; try to avoid adding references too soon or "in advance", because later you may change your mind; keeping dependencies to the absolute minimum and adding them only as needed all the time is much easier than removing redundant dependencies later;
• Remember: System is no different from any other;
• Never forget to shave all you create with Occam's Razor! See also: .