Now, if you toggle the default value of the property Delay Validation and set it to true, the validation will be delayed and the package will not be validated at design time.

This is inaccurate. To skip design-time validation of the File System task, you would set the File System task's DelayValidation property to true. Doing so, does not affect the design-time validation of the rest of the package.

An accurate statement would be:

Now, if you set the value of the File System task's Delay Validation property to true, the validation will be delayed and the File System task will not be validated at design time.

Note also that setting the property at the package - or container - level will not affect the design-time validation of contained components ie: components do not inherit the DelayValidation property of their parents for design-time validation. Conversely, in run-time validation, components do inherit the property value from their parent. Moreover, a DelayValidation property value of true at the container level cannot be overridden at run-time by contained tasks or components.

Check out Arshad Ali's article on package validation[/url] for more on design-time and run-time validation.