Do you have an ileostomy? With my output, there's no way the skin around my stoma could tolerate an appliance that long. I try for 3 days tops. In the early days, I used to be more ambitious and more frugal and felt like I'd failed if I hadn't got a week's wear out of one wafer, but I found that even if it doesn't leak, over such a long period it gets so saturated that the skin around my stoma gets converted into raw, chemically-burned, bleeding meat. I also gave up on using "heroic" methods, the tapes and strips and adhesives and other stuff; too time-consuming and costly. There was a time after my first surgery when I had to use all kinds of things because I basically had no stoma ;(it was lovely), but after I got it revised I decided to just go with a plain wafer, and if it lasted only a few days so be it.
Just now I noticed a post from someone about how going to bed with a full stomach can impact how long your appliance lasts; never thought of that. I'm going to experiment and see.