I have not broken out system partitions since my first install of Redhat 5 12 years ago and I was very confused about sizes. It really is more for servers and then the use of the server.
Herman on advantages/disadvantages of separate system partitions post#3
My 64GB SSD has two Ubuntu system partitions including /home. But I have all data in either a NTFS shared or ext3 data partition on my rotating drive. I also have swap on the rotating drive just to have some but find I almost never use it with 4GB of RAM. The only reason my /home is 2GB in my working install is the Windows version of Picasa is still in .wine in /home. My total install with /home in my working install is about 9GB.
fred@fred-Precise:~$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sdd3 28G 8.7G 18G 34% /
udev 2.0G 4.0K 2.0G 1% /dev
tmpfs 791M 1.0M 790M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 2.0G 128K 2.0G 1% /run/shm
/dev/sdc2 100G 32G 68G 32% /mnt/shared
/dev/sdc6 97G 44G 48G 48% /mnt/data
/dev/sdd4 28G 4.4G 22G 17% /media/Quantal