Whether or not I go to a lecture depends on a number of different things... whether the notes are posted online (they usually are), how hard the subject is, whether I have to go to the lecture to understand the content, what time the lecture is on, what else I have on that day etc... but generally it comes down to basically whether the lecture is an effective use of my time Most of the time it is not, so I don't go.
Lecturers will tell you that people who go to lectures get better marks, and while that may be true in general, going to lectures can be completely irrelevant to determining marks depending on the subject. Last session I went to 2/13 lectures for one subject and 3/13 for another and got HD's in both of them.
My suggestion is not to just go to all the lectures for no real reason. Go to the first one or two and figure out of they are an effective use of your time. If not, don't go. If you get special bonuses for going to lectures, like answers to sample questions, factor that into your decision but don't automatically go to lectures because of it. I saved a good 60-70 hours by not going to lectures that I didn't need to go to last session. That is a lot of extra time that I was able to spend on more important things like assessments.