I work for a Software company, in the US. My manager always reschedules or shows up late for meetings. They often cancel one to one meetings that are scheduled bi-weekly.
Even though it does not affect my work schedule, I feel annoyed about this as I am very organized and don't like a change to schedules or plans. I agree that they are very busy, with many issues to handle, but I value my time. I would ignore it if this was once in a while, but this has happened many times, and with everyone else in the team.
Also, I am talking about important meetings like planning etc (I'm a scrum master). Irrespective of whether it is an important meeting or not, I am generally annoyed with this kind of behavior which I perceive as rude and inconsiderate.