You can partition as you have done, but it can waste space and make it
harder to re-configure your system if you want to make changes later. My
computer has 17 partitions spread across three drives. I use different
partitions for installing different distributions. I have a one home
partition on each drive that is very large and I use a different user name
for each distribution. I can easily share files and setting by simply
dragging them from one user space to another. For example, I use roy as my
user name in my everyday distro, Kubuntu 9.10. I also use it for the user
name in my experimental Kubuntu on a different drive and home partition.
However, if I install Fedora on one of those drives, I use the same home,
but call my user name roy-f. I can easily import my setting from Kubuntu to
Fedora by copying files from my roy folder to my roy-f folder. That way I
keep my bookmarks, email, etc.

I try to spread my distros around in such a way that no two on the same
drive will have the same user name. I would put MEPIS on a different drive
from Mandriva, for example, and /home/roy-m would exist in the home
partition of that drive but be for a different distro.

This organization has evolved as I have been installing distributions for
ten years. Sometimes I install 3 or 4 distros a week and keep them around
until I tire of them. I have not lost any data because I know where things
are and what they mean. I can't say the same for grub which I am constantly
editing and re-installing; the perils of have multi-boot system.

As for root, I keep it simple. For my main distro I set the size of root at
30 GBs and smaller for distros that I am only trying out. One drive may look
like this, sda1 is 200 GBs and I use it for home, sda2 is 30GBs and I use it
for Kubuntu, sda3 is 20 GBs for Fedora 12, etc. In the past these numbers
were smaller because drives were smaller. I used to have separate homes for
each distro and root may be broken up but found that it was wasting space
and restricting me because such a setup was inflexible for my purposes which
is to play around with as many distros as I can. BTW, I also have distros on
usb keys and SD cards. There is no limit to the fun that you can have!

I seldom upgrade. I prefer a clean installation because installing is second
nature to me. If you are organized and have a simple setup it is easier to
keep things straight. I also label my drives so that I know what is where.
My home drive is labeled home, my Lucid installation is on my experimental
partition. I will re-install it on my main partition and eventually install
10.10 on my experimental one.

This works for me. Admittedly it is extreme for most people. I would not
advise anyone to copy what I have done. Each person needs to develop their
own style and do whatever works for them. The key is to be consistent. You
can fine tune things as you learn more and find what works best for you. Do
not fear installing and re-configuring your drives. That is how you learn.
Always backup before you try anything radical.

My advice to most newbies is to use one partition for everything, but to
work towards the goal of having it on two partitions, one for home and one
for root. If the user is more risk tolerant or more experienced I would
advise them to use two partitions from the beginning. It just makes life
easier in the end. You never need to format home and you can keep the same
data and settings for years. Re-installation becomes a breeze. I even save a
text file of applications that I use and just have Synaptic take care of
installing each package so that after installing. I can have my cake and eat
it too. I get a fresh installation and the same set up.