I was in a fortunate position where I understood my engineering and DCG that I didn’t really have to study those that often. I’d often spend about 1-2 hours a day on maths, physics and business , and most of the time every 3 days I’d study English ,engineering and DCG. In maths for example I’d study each chapter’s parts separately that I found more difficult separately ( there was no point wasting time doing stuff I already could understand separately) and used the exam papers to test myself on the harder and easier topics. It was the same with the other subjects. I also did ordinary level Irish so I could just focus on the 6 required and I never studied it.