Workout is a set of drush commands used to flush out error and warning messages that get created when pages are rendered for viewing.

Attempts to Exercise / Load every public page on a site anonymously.
You can pass in the number of pages to limit the processing to as arg1.

Workout is multi threaded. Each thread can Exercise / Load a web page.
This allows testing many pages at the same time.
This greatly reduces the amount of time required to load all the pages on a large site.