Great answers have already been given to your question, although I will reply as you asked
.
If everything was perfect, you would indeed achieve such an increase, with dual parallel and 25A batteries 50A for example.
In the real world though, things are not perfect, which is why the 50% margin is used for safety. It is likely you can push more than this safely, but without knowing how far you can really go it is better to stay on the safe side of things.
I gather it is power you are after seeing as you are building so low? I see you have a Noisy cricket V2, have you thought about running this in series instead of parallel? With this you can build higher but still achieve a very powerful vape.
For example, lets use 0.5. In parallel, you would get at a maximum just over 35W, at 8.4A.
In series, still at 0.5, this would give you a whopping 141 Watts! The amp load would be 16.8A, so still on the safe side of things. You also NEED to build coils with a lot of surface area for series, so if you want power, big clouds, using big coils, series is great.
Make sure you follow all of the standard safety precautions and you will be fine. It really is a different beast series, and until you try it is very hard to explain the type of vape it gives.
For the parallel, I would stick to 30A as this is the 50% limit. Never worry about asking lots of questions, it is much better you do than have an accident- I probably did peoples heads in when I first joined here with questions that seemed so simple.
Even if I was 99% sure of an answer, I would ask, and I still will now. Better to be safe than sorry!