alt Hacker NewsThere is literally no time involved in avoiding interest. You pay your complete balance when it's due. As far as rewards go, I can't be bothered with them so I always just opt for cash back which I do maybe twice a year. Time involved: 5 minutes / 6 mo.
There's plenty of time: the time you waste by not spending money you don't have. You have to wait longer until you make more money in order to spend more without interest.