I think a mass fab is probably the only thing where you'd need that much output, but if you have a big CASUC reactor, you may need to be able to handle 2048+ input, also.
I usually spec power rooms with 4 series ranks of MFSUs wired in parallel.
You can think about it like this:
- series: increases capacity
- parallel: increases throughput
How would MFSUs in series increase the capacity over a parallel configuration? You've got the same number of storage units wired up and since it's packet based, the current sinks on the other side will only draw what's needed.