"There are two ways to learn something - One is through pure logic ie, from first principles (building up a concept). The other is mnemonics (To help retrieve info quickly... To avoid all the time and thinking taken to derive it).
The best thing is to learn both ways. If you forget the mnemonic, you can derive it from the concept. If you forget the concept, you'd at least have the mnemonic." - SG
Many people question whether mnemonics really help. This is what I have to say in explanation. Learn both like SG said. They'll help if you manage to remember, if you forget, you can use your knowledge and understanding to come to the same conclusion.
SG is a good friend and is very philosophical on learning. These are some random thoughts that she sent and I thought of sharing them because I strongly agree!