Vlad Drumea explains why page compression might not give you quite what you expect:
I recently ran into SQL Server’s page compression being applied to a heap, and I figured I’d cover why that won’t work how some folks expect.
SQL Server’s page compression is really neat when applied on tables and indexes that are good candidates for it.
Even more so in cloud environments where storage costs can quickly add up.
Honestly, this is just a good reason to push for clustered indexes on all tables in SQL Server. I’ll call it good reason 5 out of 12.