I can only tell you from my use case which is large data transfer, when I transfer a 40GB 4k movie file on the prebuilt it will write between 300-500MB on the prebuilt but that only last for the first little while, then it tends to drop down to around 150-200MB's, with my NVME drive+enclosure its spike just like the prebuilt but the spike is around 700-1000MB's then its drops down to around 300-500MB's and can dip all the way down to 200-250MB's but again this is only if I transfer off of my NVME SSD drives if coming off of an HDD it will get as low as 100MB's but going from NVME to NVME+enclosure those dropped down speeds stay pretty steady, there is a lot of variables when doing data transfer IE what you going from and too you know NVME to NVME is always much higher then say even NVME to SSD or HDD.
if the file size is much smaller IE 4GB size then it stays at the max speed pretty much for the whole transfer
So it really depends on your use case if your using it as an installer or to run an OS off of it then what matters is what it's writing too whether it be HDD/SSD/NVME, use case matters a huge IMHO cause if its used to run an OS then I would go with the fastest drive I could get if its just for installing on loads of different system type HDD/SSD/NVME then a prebuilt should be just fine, but it also can get a little mess when you start to consider price and QLC vs TLC, I personally do not own any QLC drives cause I want the fastest longest speed I can get.
its a lot to consider I know, I would suggest getting something that fits into you budget with the best speeds you can get, shopping this way makes it a little easier lol