Smart sizing of events based on to-do item

This may be a challenge but I often find myself having to resize the tasks I drag into the calendar. I feel like if you have enough information in the task written could you make a guess on the sizing.. for example if it’s a quick thing like “send invoice”.. could this be dragged in as a 15 minute task as opposed to say “Wireframe session” where it would drag for say an hour block?