How do you assign reference designators to parts in the design?

Part References are critical in a schematic design. This is how we read or navigate the entire design. Assigning correct references is critical in the design and board layout process.   

The annotation feature assigns reference designators to all components or selected components while placing them on the schematic page automatically. Organizations follow different standards or patterns for reference assignment which helps in easy reading of the schematic, generating reports, simulating it, and locating the components on the physical board.  

With the complexity of designs increasing day by day, which of the following method will you prefer to annotate your design?  

1. Components can be incrementally annotated as per placement from left to right or top to bottom of page.
2. Parts are placed without part references initially and the entire design is annotated after completing it.
3. Annotate the design with page level or block level controls.
4. Component are assigned references based on their part reference prefix.
5. Use custom script to assign reference as your requirement 

Let us know if you use any other method for reference assignment. 

Regards,

Yugandhar.