The only way I'd take a break is if I was staying over 2 weeks. I've taken kids to Disney at age 4 months, 18 months, 4, etc. and a midday break is the perfect way to recharge. Plus, there's usually a few naps in the stroller throughout the week. I wouldn't "waste" a day in Disney if I'm only there for a limited time. We've never once had a meltdown in Disney, so I'm sticking with that plan for our upcoming trip. The key is to be flexible, within the limits of ADRs.