足足 + Amount (a full / as much as)

A whole hour, and I counted

• fully足足zú zú + (amount) = "a full / as much as / no less than".
• fully足足zú zúto wait for等děng(completed / change)了le一个yí gèhour小时xiǎo shí = "waited a full hour."
• fully足足zú zú stresses the amount is bigger than you'd think.

fully足足zú zú + Amount

• fully足足zú zú underlines a surprisingly large quantity.

I我wǒa full足足zú zúwait等děng了leone一yí(measure word)个gehour小时xiǎo shí。

• fully足足zú zúto wait for等děng(completed / change)了le一个yí gèhour小时xiǎo shí = "waited a full hour."

Recap

Read the full reference: HSK 6 grammar — Adverbs.