-w is for the workload profile, see the output of the hashcat --help command:
you could say that -w 3 actually would be optional, but it's always recommended to think about this option and how to likely improve performance
Code:
hashcat --help
...
- [ Workload Profiles ] -
# | Performance | Runtime | Power Consumption | Desktop Impact
===+=============+=========+===================+=================
1 | Low | 2 ms | Low | Minimal
2 | Default | 12 ms | Economic | Noticeable
3 | High | 96 ms | High | Unresponsive
4 | Nightmare | 480 ms | Insane | Headlessyou could say that -w 3 actually would be optional, but it's always recommended to think about this option and how to likely improve performance