I agree with Benjamin Kaiser's response. I'd like to add two more points, though.
First, you shouldn't be resizing partitions on a regular basis. In addition to being a time-consuming operation, partition resizing is risky. This is especially true if the partition resize involves adjusting the start point of the partition, which requires a great deal of the filesystem's data to be rewritten. A power failure, a bug, a system crash, or some other problem can cause damage to the filesystem that will be difficult or impossible to fix. Thus, you should resize partitions only if doing so is absolutely necessary; and when you do resize partitions, you should be prepared to lose all the data they contain. If that data is irreplaceable, you should make a backup before resizing the partition.
Second, if for some reason you need to resize partitions frequently, you should look into logical volume manager (LVM). This enables you to treat filesystems something like files, so that you can add, remove, shrink, and grow them without worrying about start and stop points. This means that you'll never have to adjust a filesystem's start point, thus taking some of the danger out of the process. Unfortunately, Ubuntu's LVM support is weak, especially for desktop editions. LVM is also more complex than using partitions directly, so it'll take some learning, and the complexity can make recovery more difficult should something go wrong. Still, if you need to juggle your partitions a lot, LVM can be a net plus.