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
