Output type Configuration for inbound deliveris

Hi,

I am configuring a new output type for inbound deliveries.

I created a new access sequence and assigned to output type.

Access sequence contains 3 condition tables assigned. Here , there is a option to assign requirement routine to condition table.

Then I assigned Output type in 'Output determination procedure '. I see option to enter requirment routine in this step as well.

Could you explain why there are 2 diiferent options to enter requirement routines i.e.  one at access sequence level and other at output determination procedure level?

And also at access sequnece level , what are the scenarions where we need to assign different requirement routines to different condition tables in same access sequence?

Thanks

Terry