Which accounting concept applies when a work sheet is prepared at the end of each fiscal cycle to summarize the general ledger information needed to prepare financial statements?

The statement is called the trial balance.
This is a summary of all the ledger accounts.
In the double entry system , by definition
the total of all the debits must be equal to the total of all the credits.
When this is O.K, you can then proceed to
prepare the financial statements, that is
the Profit & Loss Statement for the period in question and the Balance Sheet as at
the date of the statement.

The worksheet is used to determine if your accounts balance and to assist you in preparing your financial statements.