We always recommend that you try not to schedule a class unless you've made sure you can make every session. That being said, we understand sometimes the stars don't align and missing a class or a few hours can be inevitable!
Making up a missed class may not be possible with every school, so we definitely advise you contact either us or the school directly if you're worried about that. Also, please note for many of the shorter classes (1 day or less), the school may not allow you to take the class if you show up too late.