"Tú necesitas rostizar el pato por aproximadamente una hora."
Traducción:You need to roast the duck for about an hour.
Yes, it is OK.
However, if it modifies a specific word or phrase that is not the verb, usually the adverb goes before that which it modifies. ("It was really fun."-- but for emphasis, "Really, it was fun." )
If it modifies the whole sentence, it tends to go at the beginning (or the end), depending on the emphasis. ("Unfortunately, that was a mistake.") ( "Realistically, we should...." )
However, what I have just stated is simplistic. See these references.