So I'm gonna schedule my standard GRE for a week from today... I went through some of the practice questions online and it seems almost like a joke to me. The quantitative is pretty simple for a physicist, the vocabulary certainly isn't mind-bending, and the writing I didn't even really look at.
Is it worth taking time away from my actual studies to spend time preparing for the general test, or should I just wing it and go cold?
Do one practice test. The writing part is the only nontrivial thing, so it may help to practice it a few more times if you are not comfortable with it yet. Also it may help to read through the pool of topics for the writing parts, so you know what you can expect. I took one practice test the evening before and got 170/169/5.0 on the real one, so that should suffice.
Just look over some of the math questions in case you forgot how to do some of the things from high school math and do some of the critical reading questions. Maybe look at the guidelines for the writing section. I spent a total of about 2 hours studying for the test. I actually didn't even know the format for the writing section (which I actually did well on scoring 5.0). My score was totally fine. 168 quantitative and 162 verbal. Honestly just aim for somewhere in the mid to high 160s for the quantitative section and maybe about 70% for writing. No one really cares. At an REU I did they showed a graph of the GRE scores versus the acceptance rates which basically confirmed it doesn't matter as long as you don't do poorly on the quantitative section.
I just want to point out that a few professors I've talked to stated that the writing score is a better correlation of how a student will perform in grad school than the physics GRE. So, you know, you should probably prepare for it.