Thanks for all your insight!
I have a separate drive for my operating system and just personal local files.
I then have 4 other hard drives, but 2 of them mirror each other. I am a wedding videographer and we typically fill up 2tb over a summer wedding season. I hold everyones footage for at least a year, so I end up getting new drives every 4-5 months, they don't really have a chance to get old.
2 of my drives are in my tower.. but the other 2 are connected via an external docking station connected through a usb 3 connection. I imagine that is not the best to have 2 drives running through 1 usb connection. As you said it is like a highway and that sounds congested!