How to make hex rivet nuts aligning to hex holes faster ?
If the hex holes were created using patterns, then you can use Pattern Component with the Reference option.
This will fill all of the holes with rivets after placing the first one.
Another solution is to use Assembly Constraints. Refer to 'Remember Constraints' in the Help Documentation.
Having a 'no constraints' policy in place is something that you may want to re-evaluate.
Use Move Component>Transform> Constraints>Centre ; Subtype> 2 to 2;
Then select two opposite faces of the moving part and then corosponding two faces of the hex hole.