Avoid juggling multiple meetings at the same time.
Calendar, you can check your appointments to see if a new event would conflict with your schedule.
When creating an event, tap
Press and hold the event box, and then drag it to an available time slot.
Drag the directional arrow buttons to adjust the event's time duration.
You'll see a message if there are conflicts with other scheduled events.
Done to return to the new event screen, and then tap