For a long time, I also stuck to 70/30, probably because I watched a lot of Tamás Fehér. When I started, he was everywhere. Then I got many good tips here @Zolika 
thank you. The point is, nothing will leak even with 50/50 if it’s properly put together, maintained, built.
And it’s absolutely true. Currently, I mix 55/45 + the flavor in RTA, Aio, RDA as well.
And we know, the more PG, the better the flavor.