If at the end of the final challenge you need a few extra points to pass, then the extra mile points may come in pretty handy.

thats right, and they mainly go deeper into the subjects that are treated. i learned a great deal from these, so i suggest to do them...besides, there fun!

Yep, they only come into play if you're very close to the passing score.

There's extra miles for OSCE as well, but not sure if they count or not, didn't have to use them   But the challenge was fun indeed  

If you do a course you love, why not dive into it's fullest extend? 

err, you can feel if the water is cold with your toes, no need to go skinny dipping right from the start 

most of the extra mile challenges are within the first parts of the course. have a go at them first, then dive into the labs. it will give you a nice overview of the steps that need to be taken to hack the labs. Good luck and remember, if you at first don't succeed, try harder (this is never getting old)