Should I even bother with GREs?

For me, "more free time" usually means "more time to worry about the future". I have a lot of things that I've previously put off worrying about, but now I have the time to worry about them. I need to book my driving examination because my licence expires in September. I need go to an optometrist because my prescription seems a bit off. I need to learn a particular statistical test so that I can wave possible results at my supervisors and possibly move along the writing of a manuscript. But lately what I've been thinking about the most is GREs.

I need to do the General GRE soon, probably in the spring. That means I have to start studying and setting deadlines to motivate myself (I can't pick a specific date until I know what my exam schedule is like). I also need to start thinking whether I should do a Subject GRE. This is more problematic because I really don't know if it's worth bothering with. I'm confident that with a bit of prep I can do well on the General GRE, but I'm not so sure I can manage a decent score on either the Biochemistry, Cell, and Molecular Biology or the Biology test without a lot of studying. I've looked at past tests and the amount of detail that I would have to relearn is staggering. Additionally, I would need to learn about subjects that I have barely touched previously and will probably never really look at again in greater detail. None of this is that objectionable in principle, but the time I would have to put in is insane. It is especially insane when I my plans for the summer include doing research and taking a course.

Taking a Subject GRE seems even more pointless when most of the schools I've looked at in the US only recommend taking one but don't require it and Canadian schools couldn't give a rat's ass about GREs at all. What I want to know is if there is actually any significant benefit to taking a Subject GRE and doing well. And if there is some advantage, does it outweigh the cost I pay in time and anxiety?

Right now I'm leaning towards not bothering, but I'm open to changing my mind.