Why is the aging of accounts receivable usually more accurate than basing the estimate on total receivables?

Question:

Why is the “aging” of usually more accurate than basing the estimate on total receivables?

Accounts Receivable
Accounts receivables are debts owed to your company, usually from sales on credit. Accounts receivable is business asset, the sum of the money owed to you by customers who haven’t paid.The standard procedure in business-to-business sales is that...