How integrated planning : Planning sequence works

Dear Experts,

As i understood that planning sequence will always read all the data from

the cube and will be processed as per the planning function we select.

Then won't this duplicate the data as the same data is being read every time

planning sequence is run along with the new data, if yes how this is being handled.

Is their any underlying functionality which is working so the planning sequence

will not process already processed data (like delta mechanism in regular BI)

Can somebody give me some step to step understanding of the imp planning functions available

along with some example scenarios.

Thanks and Regards

Neel