You should use the diffuse mode of thinking, as the diffuse mode is the one that processes abstract ideas.
You should study very intensively for one day a module, as this is the best way to create strong neural connections. After a very intense session of study you will have already learned that concept, and you won't need to study it again.
You should practice regularly, as practice strengthens the neural connections you make during the learning process. The concepts you are studying might seem abstract, but strong neural connections are real and concrete.
If you are not “naturally good” at mathematics, you should consider studying something more in line with your natural abilities. People should only do what they are naturally good at.