Accrue on receipt and Accrue at period end

Hi,

I would like to know the use of accrue on receipt and accrue at period end functionality.

Accrue on Receipt - Normally accounting entry will generate once receipt is created

Accrue at period end - Accounting entry will generate at period  end by running the "Receipt Accruals - Period end Process"

Anyway both(accrue on receipt & accrue at period end) accounting entries are getting generate in single month only. so how this functionality useful in business perspective.

Regards,

Madhu