【One Idiom】on the go

I have been using this idiom as sth. being in the process.. e.g.

We do what we can do now and keep adding more on the go. 随时随地..

But seems I heard some other meanings of this idiom.

So I googled, yes, it can also mean very busy.

e.g.

• very busy

He has only one hour left to catch his flight, he is really on the go. 

 

 

• in the process of being produced:

Did you know that she's got a new book on the go (= being written)?