Why must the eliminating entries be entered in the consolidation worksheet each time consolidated statements are prepared?

The reason to prepare the consolidation worksheet is to maintain the record of what is finally entered in the books to record the transactions in between the holding and subsidiary.

This basically thus, requires the elimination of all the assets and liabilities of the subsidiary, and creation of such assets and liabilities into the balances of the holding (parent) company. In this manner the elimination is necessary to record.

So that there is no error in the form of multiple record of assets and liabilities, or in the form of no record of assets and liabilities of the subsidiary.