It's always smarter to run Windows OS or mining OS through flash drive, why ? Those things are cheaper than SSD and you can replace them easier also they draw lower watt through USD port compare to running HDD and SSD combined but my question is how lasting are flash drives? Are they reliable ?
Nowadays the cost of a USB is really cheap,you can find 64 GB ones for 5-10 USD in Aliexpress,you can make cloning of them after you achieve the best possible options in your OS with Acronis (software for cloning disks) and you can have like 3-4 of them as backups when bad things happen.Normally they last long enough as I have one running from 2018 and no problems so far.So yes nowadays the technology has evolved that much that they are reliable,I am talking about branded ones like Sandisk,Kingstone etc and not the Chinese non-branded USB-s,those probably won't last long.
+1
Small SSD are damn cheap.
For the mining linux oses i use…a good quality flash drive has lasted more than 5 yesrs. All my rigs have Sandisk 16 - 64gb mem sticks. I have a total of 58 rigs and no issues. Windows i could see being a problem as it will want to write to the drive constatntly. Mining Oses specifically designed to run off mem sticks do not constantly write to the thumbdrive.
I have build my own Windows OS and stripped of everything that i don´t need -> it writing nothing constantly to the drive.
And there are also Win10 images out without installation, which will boot and run from USB flashdrive -> this versions also don´t write constantly logs.
HiveOS is writing constantly a log, you must deactivate it, if not it can kill your flashdrive. So not all miningOS are for flash drives out of the box.