Every account is its Own Account. Organizing them under Parent Levels = makes the reporting easier to read, rolls Up the totals for reporting, and allows you to Expand and Collapse the reporting.

"In those cases am I correct not entering a tax-line mapping for the main account?"

Your reports should reveal if you ever posted to the Parent, which is a typical Error. Once you have that structure, you post only to Subaccounts. Otherwise, you see this:

Insurance <== Parent

General Liab <== subaccount

Worker Comp <== subaccount

Insurance - Other <== error in the entry