Reports processing

Our Piwik implementation is presently running on two server nodes.
The first node runs every 2 hours, starting from 00h.
The second node also runs every 2 hours, but starting from 01h.
As you can see, we have an offset of 1 hour between the two processes.
However, for processes lasting more than 1 hours, which sometime happens, the two tasks overlap each other.
So, should we avoid processes’ overlapping or, on the contrary, maximize it? What do you recommend?
Thank you.

You can try run the task every 6 hours or so instead?