Unfortunately, changing the Start and End times of an APPOINTMENT will not
cause it to take up less space - you can test it this way to see:
double-click on your calendar to open up a new appointment, and manually
change the end time to be the same as the start time by clicking on the
drop-down box next to End Time. You will see that it still takes up the same
amount of space on your calendar as if it were a 30 minute or a 60 minute
appointment.
Another option, though, is to use the instructions I gave you before, but
change the "Time Scale" to 60 minutes (which is the largest scale you can
choose). This will change your Calendar View. With the 60 minute setting,
your calendar view shows you about 17 hours of your calendar, as opposed to
the approximately 7-8 hours of your calendar that you see when the Time Scale
is set to 30 minutes.
Good luck!