The value of the hash is independent which amp the row ends up. There is a hash map that determines what hash results map to which amp.
If you have a system with 240 amps and a table with a UPI that only has 50 rows, you will NOT get even distribution, as there aren't enough rows to map to every amp.
The even distribution of a UPI is a happy by-product of the hash map. Remember even distribution of data is a secondary consideration of PI selection. The most important consideration of a TD PI, UPI or NUPI, is the most common data access path.