I’ve read through warranty policy for many main HD/SSD manufacturer and found
Transfer speed 1050 Mb/s!
I don’t think that it is a bottleneck.
It’s not going to be as fast as an internal, but on one machine I do use a samsung t5 external as a temp folder for one plot, the internal drive for a parallel plot… both dumping to a samsung t7 external. (I have 7 different machines plotting)
your t5 is bottleneck?
have you tried benchmarking with typical NVME or ‘internal’ SSD?
If the speed is not a bottleneck for plotting process, the “no TBW warranty” probably outweighs the slightly lower speed.
You need to be careful with these external drives; there are two limits
interface method (USB 3 5gbps, USB 3.1 “superspeed” 10gbps, USB 3.2 “superspeed 20” 20gbps, Thunderbolt 3 40gbps)
drive media speed
I recently got bit by this HARD, two times…
Samsung QVO 8tb SSD. They are cheap for a reason. Fast until you blow out the cache, which is only like 70-150gb … then the write speed degrades to max 150mb/sec.
Crucial X6 4tb portable SSD. Works great, until you get past around 700-800mb, then everything slows to a snail’s pace of 80mb/sec … both read AND write! 
I returned both of those. I was kind of aware of the QVO limitation, but once I learned spinny rust can easily do 200mb/sec (well, until it gets about half full) and stays at 150mb/sec for quite a while, there was no reason to pay all that premium for a QVO SSD.
What I am liking lately is external 2.5" SATA SSDs. These are inexpensive and mature and can almost always maintain a solid 300-400mb/sec reading and writing for the entire 2TB / 4TB space.
@codinghorror this one can sustain at 970 MB/s writing speed. Cannot find the full ref for WD and Samsung though.
I’ve tried to find articles on the speed drop off. Do you have suggested reading on the cache stuff?
Consumer 2.5" Sata SSD has very low TBW. The intel and server one are the best bets but I cannot find in my area.