How I interpret the setup that OP has, is that he some computer (a PI, an old laptop, a NUC, etc.) which is connected to drives in an external drive bay through USB. This is a somewhat common setup and is definitely a NAS.
> For data use cases like this, USB 3 can be reasonably comparable to Thunderbolt 3, and that connection is generally faster than the media.
External HDD enclosures can often contain 4 drives. During a resliver all of these could be heavily accessed. I'm not sure how the single USB 3 connection fares in this scenario. In a normal desktop you'd have four separate SATA connections, and even then resilvering a large RAID setup can take quite some time.
> For data use cases like this, USB 3 can be reasonably comparable to Thunderbolt 3, and that connection is generally faster than the media.
External HDD enclosures can often contain 4 drives. During a resliver all of these could be heavily accessed. I'm not sure how the single USB 3 connection fares in this scenario. In a normal desktop you'd have four separate SATA connections, and even then resilvering a large RAID setup can take quite some time.