I have recently learnt this good idiom but would like to understand it better. 

The dictionaries say mostly;

> 
> in einem Rutsch = in one go
> 
> 
> 

I have thought **in einem Rutsch** as the synonym of **auf einmal** until now. But it is not sufficient to think like that.

For example, there are three tasks, which should be completed.

When I say;

> 
> ich möchte die Aufgaben in einem Rutsch
>  erledigen.
> 
> 
> 

does it mean more, 

> 
> I will (work on) complete all of the tasks concurrently 
> 
> 
> 

or 

> 
> I will complete them consecutively (in a row) without giving any break?
> 
> 
> 

Addendum
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A follow-up question: Which word should be used to give the sense of concurency, while the tasks are being completed?