If only I came across this about 4 years ago.
Actually, it's more efficient to just do better on the LSAT than stress about every last homework assignment in undergrad. Every last question on the LSAT matters a lot more for admissions than the "every decimal" for GPAs. The main problem with law school GPAs isn't really the slackers. It's the over-committed students who put extra-curriculars above academics because they don't want to disappoint the other people in their clubs, groups, sororities. So don't stress about everything, get a 3.7-4.0, and when there's a conflict between extras and academics, choose academics.