This question was closed as being primarily opinion-based. The question originally asked "how much time do you spend on reviewing a paper?". Put this way, the question was a bad fit for the Q&A, because it amounted to a poll (although, strictly speaking, it wasn't opinion-based).
I've edited the question to focus on the aspect that is of more general relevance, and which arguably was also what OP intended to ask: "How much time should you spend on reviewing a paper?". I gave an answer based on an objective criterion, namely that the time should be appropriate to the task. This clearly is not primarily opinion based. Moreover, we have several open questions asking whether this or that is "ethical". I feel, if these questions are not primarily opinion-based, neither is the present question.
I had hoped to read other answers to this obviously relevant and important question. It should be reopened.