Can I use editions from previous years to study for standardized tests like the GRE, GMAT, LSAT, etc.?

Answer 1

I can only speak to the LSAT, but, absolutely. After you have a solid grasp on the basics, using old official material is the best way to practice and improve.

Answer 2

Absolutely - prior year editions contain essential questions that are often incredibly similar to what you will see on exam day.