Multiple HDD setup for DAW

I have recently installed 2 more 1TB 7200 RPM drives into my existing PC from an old PC, giving me a total of 4 drives, as I already had 2x2TB 7200 RPM drives installed, I dont have any SSD drives as yet as have been waiting for the price to become more affordable for 1TB+  models.  I only have 2xSATA 6GB ports and 4XSATA 3GB ports on my current board, and have one of the 2TB drives as C: drive.
 
For the long term I not really worried about drive sizes as storage is pretty cheap and I will be uprading them too SSD as finance and practicality permits, are more concerned about drive mapping and path dependencies for software for thing like Komplete Ultimate, Omnisphere, and even Sonar/Addictive drums etc.
 
I have external 5TB USB3 drives for backup, so backup is not required on internal drives.
 
I will need to update my PC in next 12 months as 1155 socket machine so is a waste of money upgading RAM, or replacing the i5 with a i7 etc, in fact most suppliers dont even have the cpu's available for it now.  But I will simply replace the mainboard, cpu and memory and move the drive setup across when I do this so will keep the same drive setup.
 
What my question is, what is the best standard practice for a 4 drive internal setup, should I use one drive just for Komplete and its dependent libraries and a separate drive for my other synths, should I use and internal drive for projects, or use an external USB3, should I uninstall my DAW's and put them on a different drive and just have windows and cache files on C:, etc?
 
I am hoping to get my drive mappings right before unpacking and installing all the stuff I have purchased over the last few months that are not installed yet, so I dont have to go through the pain of doing it all over again, because of creating some bottleneck that could have been avoided by smarter file organisation across drives.
 
So people other musically inclined beings, what drive layout makes the most sense, and is easilsy manageable in these days of cheap mass storage devices?

No standard practice and not really a rocket science. Do as you wish.

Cactus Music
One thing I would change for sure is to use a SSD for your C drive. A 1TB C drive will be 90% empty if you follow what most do and use it for OS and software.  
I have a 240 in my DAW and it's using 40% of it's capacity. I have a lot of programs in there and didn't change the pathways for Sonar. 
My office computer only has a 120 and it's at 45%. 
DAW's seem to need bigger C drives but a 1TB os overkill. 
The preformance gain is worth it, once you've used a SSD drive you can't go back. 

At the current time my C: drive has for the first time in years been reduced to under 1GB, I have a full version of MS Office installed, several photo and video editing swares, games, windows 10 recovery partition etc.  I have moved all documents and picture files to external storage, and are wondering what programs to uninstall next.  It was at 1.3GB with no music samples or documents on it.
 
I have a lot of very large installs on it, and I really dont want to download them again, where I live, it takes approx 1 hour per GB for downloads. Think it took me something like 2-3 days to install Sonar Platinum!
 
Yes, I do wish to have my OS drive on SSD, but at moment it will not fit on less than 1GB if I want at least 10% free space.