Parameters That Affect PDC Bit Performance
The performance of a bit may be judged on the following criteria:

- How much footage it drilled (ft).
- How fast it drilled (ROP).
- How much does it cost to run (the capital cost of the bit plus the operating costs of running it in the hole) per foot of hole drilled?

Cost Per Feet

Since the aim of bit selection is to achieve the lowest cost per foot of hole drilled the best method of assessing the bits’ performance is the last of the above.
https://www.drillingmanual.com/pdc-bit-performance/