Actually with the busy routine , sometimes we had to give short comments

Yes that's correct. I believe the practice will automatically leads us to put short but valuable comments.

But if we have very short comment for our post wow, superb like that, it's hard to give a good reply comment beyond saying thank you...

Yes. Same here. It's better to do as they do.. What else we do!!! It's like the world's shortest love story..
Boy : "Hi I love you"
Girls : "Thanks"
Boys:" Welcome"

Done.. :D But when you met the correct audience you'll start to love to do comments..