As others have said, this is very subjective and personal. We’ve pulled our kids out for up to a week at a time when they were younger. Last time we did that my oldest was in 2nd grade and had some trouble catching up before the end of the semester (we pulled her the 1st week in December), so that was the last time we did a long trip during the school year. Since then, we’ve pulled them for a day or two at a time, working around school breaks for all of our trips (and generally we’ve found they don’t miss much if they’re gone the day before or after a break). This year they will miss a day and a half before fall break and a day before Christmas break and I don’t feel bad about it at all. Family time is just as important as school time (if not more important), and missing a day or two here and there is unlikely to affect their studies. Now, once my kids are in high school, I probably won’t pull them for vacations at all, but for now they can afford to miss a few days! Just my opinion! (And for reference, my oldest will be in 5th grade this year.)