Hardware description and problem introduction:
I'm a Home user and I use Windows in a Home PC, I have 4 internal hard disks connected and running, 1 hard drive is for the OS, and the other hard drives are 'secondary' (They are single partitions, any RAID).
For life circumstances I need to keep my PC ON every 24 hours of every day of every week of every year (I don't have money to buy expensive things such as NATs), the PC does not sleep and does not hibernate and does not turn off, but like I've said, I'm a home user, please don't threat this question like an intensive working PC of a company.
The hard drive that stores the OS is working every minute all day, the others hard drive aren't but I access to those secondary hard drives like 20 times each day to navigate through their folders.
I would like to be sure that I'm doing things the most safe possible that I can, I would like to keep alive the life of my hard drives the maximum time possible, so taking the information that I've explained above I would like to know if in my circumstances it's better to turn off the power of the secondary hard drive devices to save power or not, in the power management configuration that provides Windows.
I ask this also 'cause I'm confused about opinions, an expert hardware 'mechanic' (I don't know the English word, sorry) said me that turning off the power of drives is not the most safer decission
IN ANY CIRCUNSTANCES 'cause it depletes the total life time of the device each time that the device re-initializes, for example when a disk is turned off automatically by Windows and then I open the Explorer to navigate inside the hard drive folders it needs to wait some seconds to turn on the device to list the folders, and he said me that those insignificant seconds at the end depletes/waste away the total life time of the disk, and it's safer to don't turn off the power of the devices
Then, what is better and safer for me? let windows power management turn off devices when they are not working, or keep on the power every time?
If turning off the power of the devices at the end it's a life-time consumer then why Windows puts an unsafe checkable option in the power management?
I'm very worried about the future state of my hard drives by let Windows turned them off/on every day 20 times when I need to read those secondary hard drives, so I'm only searching and I only can accept an answer of a professional hardware expert that could clarify my question.