A Table of Contents can be used for any Post in WordPress, no matter the Post Type. However, there are some Post Types that simply do not need a Table of Contents. For example, if your WordPress theme (or another plugin) introduces a Custom Post Type called 'Redirects' or 'Forum Topics', a TOC wouldn't make much sense for those Post Types. With WP Tocify, you can include or exclude specific Post Types so that WP Tocify only appears when it is relevant.
DashboardSettingsWP TocifyPost Type Options
Use one or both of the select menus to tell WP Tocify where it's needed and where it's not. If you tell WP Tocify which Post Types to include using the first select menu, the excluded Post Types become irrelevant; i.e., you've already built a whitelist. The choice is yours though.
Note: The WP Tocify meta box will only be shown when editing Post Types where WP Tocify is applicable, based on your Post Type Options. So by including only specific Post Types, you're keeping the WordPress Dashboard cleaner.