I was running some individual tests on some drives, I have at least 16 drives in my machine I need to test, HDD and SSD's, some w/o partitions. I'm pretty sure I was able to run concurrent tests on these drives before, so when I was running an extended test, I could run them on all the drives at once, but I forget how that is done - and in addition how to save the results to a text file (named something like dev-sdx would be fine).

IDK if running many tests at once would slow the system considerable, but I had LOTS of CPU overhead and only one drive is really doing anything, the rest are connected for this test ATM.

Is there a way to do this and how would i go about saving the results/output of each test?

I tried GSmartControl, but it has to be run one test at a time and some of them don't offer conveyance tests and others the extended test only takes the same length of the short test (60 seconds) so IDK what is going on with that piece of software. IDK if the CL option will give better results, but any suggestions would be appreciated.

I need to figure something out as I have about 130-180 drives to test, maybe a few more, and doing them individually is no in the cards ATM.

Any suggestions?

Haven't tried it but maybe smartd ?. Have a look at its manpage, and smartd.conf manpage.
Quick "onecheck" shows the device in the message - pick your own log location then post-process with grep or similar.

smartd is running well on my debian server but i remember that some manual configgering was required.