Just started Altreryx,
Did the same thing as you because I didn't know that the tool "Generate rows" existed.
I think this solution is a bit more data intensive, from the one proposed, because from 2678 rows we go to 13390 in order to pose the filter formula and separate out the data. On the other hand, the "Generate rows" way create less: 5-->20 rows and then the join tool does all the rest. I am not an expert but there is something to think about.
If there were a lot more postal ranges and the ranges were bigger then I think the generate rows would be also expensive.
Liked the test part. Nice work.