The U.S. Government recommends, 150 minutes, or two and half hours of moderate aerobic exercise a week. Studies show that you need a combination of cardio and strength training to keep your body in shape. That would control your weight (provided you're focusing on a clean and healthy caloric intake) as well as keeping your heart and muscles in good "working order."
So, five 30 minute sessions would get in your recommended amount. Mix it up, 2 sessions of weight lifting to build lean muscle, walk / run one day, swim another, tale a class the other. Split it up however you like as long as it includes some kind of muscle building and cardio.
There is no need to try and get it all in in one day and if you try and workout 2 and half hours a couple days a week, I feel your returns aren't matching the time investment. You'll probably burn out and quit as well. Spread it out, go intense on days you're feeling good, a little less so on other days. Mix up what you are doing to keep it fresh. Get a good nights sleep and repeat.