How many rows did these tables have before partitioning? à We starts test with 0 rows in partition table.
Partitions are far from free and pruning is great but not guaranteed. How many total rows do you currently have or foresee having in the biggest table (all partitions combined, or without partitioning) within the next 1-3 years? 1 million? 100 million? 2 billion? You may have partitioned before it was prudent to do so is the point. Just because something can be done, doesn't mean it should be. What sort of key are you partitioning on?
Also, what do you mean about tests? There are some assumptions made about empty tables since stats may indicate they are empty when they are not. If your tests involve many empty tables, then it may give rather different performance than real life where there are few or no empty partitions.