If we're truly irreplaceable, to the point that one day away means that students cannot still make progress in some respects, then we could definitely do a better job! (Think about a boss not being in one day: if the employees can't step up and take leadership in that moment...the boss could do a better job with their employees -- it isn't all content, it's also about those interdisciplinary skills!) In addition, I think it's important that we accept and are okay with both people who use days and who don't use days, so long as it's not harmful to the students (i.e. coming in with a severe sickness). While I've not taken any other days outside of the memorial/graduation (both extremely important in my life), that's partially due to how long I take in writing sub plans and thus it not being as worthwhile. That might change later in my career. Besides, someone who takes more days off might be fresher and might do better on those days than those who didn't take any days. Or those who didn't take days might end up finding that they got through a bit more. Or those who took days off might not be any fresher, or those who didn't take days off might not have got through any more than those who did take days off...... Too many variables, not something worth worrying about...we each are ourselves, do what we know is going to be the best for us and our kids, and move on...no judgment!