There is no actual amount of time that the Weekly Review should take. For example if you were on a business trip during the week and your inbox is piled up sky-high, you will have to process all this during your Weekly Review.
The goal here is actually to get prepared for what is to come during the next week(s). If it takes you three hours to get to that feeling that is totally fine. And it is also a matter of experience. I think once you are familiar with the procedure you can perform the different steps much faster.
Maybe you should ask yourself one question: Do you feel like you wasted these three hours or part of it?
If the answer is yes, you maybe spent some time to think too deep about stuff that was already totally clear to you.
I hope, this helps.
Cheers,
Tristan