I've been doing this stuff way longer than maybe I should have.
In the days of the Seagate 20meg hard drive, partitioning wasn't even a subject for discussion. But when the drives started coming out in multiples of gigabytes, partitioning became more wide spread.
With the large drives of today, I will NOT set up a new hard drive without partitioning it for the OS and Storage. The OS partition should be large enough for your OS and the programs you use every day.
The storage partition can be used to store pictures, music, videos and really large Software Suites like MS Office, Corel Suites, etc.
This keeps scans and defrags down to a minimum time frame and lengthens the life of the drive.
Further partitioning the "Storage" area into separate partitions for different file types is totally redundant and makes drive maintenance a nightmare.
Separating information is what Folders are for.
Folders can and will grow along with the data in them....a partition CAN-NOT.
Having to re-size multiple partitions on your HD, is a recipe for disaster.
Even an experienced tech, using the best partitioning software available, can screw that one up!
Likewise having two OS's on the same HD.
Want to run two OS's? Then use two HD's.
Eventually, you'll be really glad you did.
Cheers Mates!
The Shadow