I've noticed a big difference between aspen and pine pellet bedding. The aspen, even with just two or three mice in a ten gal tank would turn over and die roughly every week and a half. The pine pellet bedding as no smell lasts twice this long. I have a male mouse all by his lonesome and I can't remember the last time I had to clean his tank. There's no smell and the urination area dries before it can become too much of an issue. The more mice, the quicker I need to change. Even then, it'll last several weeks unless I have a water bottle leakage.