Mavericks calendar events longer than 3 hours
I use the + quick event button which is the same as Command-N to enter:

meeting from 10am to 5pm on thursday


It makes blocking specific times quite easy using Calendar app. I also often use the week or day view and create a default event and drag the bottom of the event to the end time.

Lastly, I select the hour when I mouse to raise the quick interval drop down and rather than use the mouse to change the end time, just type the hour and tab to the minutes field if necessary.