I don't agree with the test must be ran higher than Deca, Google and you will find that nearly EVERY one will repeat this, but when I tried it myself I found something very different. Test E at 300 and Deca at 500 was probably my favorite cycle ever besides Tren. I've ran it all kinds of ways. Test 500 deca 500, 500/300, 500/150 and 300/500 respectively. Test and Deca at 300/500 gave the biggest, leanest gains with minimal water retention, crazy high libido (without caber), normal blood pressure, no bad sides, and PRs broken even cardio PRs.
You will find that everyone is different and only you can find what works best for you.