Full load and Delta with a Staging table

The steps before loading the records into the data warehouse are ...

1-Extract

2-Transfrom ( cleansing and combining joins)

3-Loading the data

During the firts load we do a full load in the target table .Of course the staging table receive this full load as well.

However the second time we process the records , we do a delta in the target table .

I was thinking ... does the standards recomend to load all the records again in the staging table or only the delta has to be loaded in the staging table .

Thanks