Hey there! So this set up will catch all of your EC2 instances and find all the associated logs. It actually is a "run once catch all" deal. One of our engineers would be happy to give you more technical detail if you want. Shoot an email to support@logentries.com.
Also, is you want to give it a try yourself, we have an unlimited free version for 30 days available on our site that has le_aws available, so you can try it for yourself. Check it out: https://logentries.com
Note: The first picture in the blog post is an actual screen shot of the script discovering all of one of our engineer's EC2 instances automatically.
Thanks!