I had the luxury of focusing full-time at some points, but balancing all three sections is non-negotiable. Even if you’re working or in college, don’t let any one section drop off the radar. I used to split my day: I gave a bit of time to each of the 3 sections everyday. My preparation wasn't based on hours but the output. I made sure I did atleast 30-40 questions of quant, 2-4 sets of DILR and a sectional mock of VARC daily. Early in prep, you can focus more on your weak section, but once you’re three months from the exam, keep a balanced approach and start mixing sectionals. Don’t skip mocks, no matter what.