directory submissions can give one way traffic though it onnly gives few traffic for the site.

I'll let you know if all the backlinks shown in Google Webmaster Tools to my site from directories disappear all of a sudden

You can check your Google backlinks that Google still displaying your directory backlinks.

Remember, just because Google shows them, that doesn't necessarily mean it is counting them.

I'm not saying directory links don't help, but you need to be careful these days about which ones you use. I personally would stay away from any general 'SEO friendly' directories.

Getting a link from any directory will overall improve your rankings.

Absolutely not true. Links from the wrong places can harm your site. Read up on GoogleBowling.