Art.133(2) EPC allows applicants having their residence (or principal place of business) in an EPC Contracting State to act in all proceedings before the EPO without having to appoint (and pay!) a European patent attorney.
Have you ever wondered how often applicants actually do that?
The answer is 4% of the cases.
Out of 140000 granted European patent documents (from 2019), we have found about 6150 patents not having a professional representative on file.
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A note for EQE candidates:
It is important to remember that Art. 133(2) deviates from Art.14(4) EPC! As an example, an Italian natural person living in the USA must appoint a professional representative (for acts other than filing), but he/she can file documents (to be filed within a time limit) under Art.14(4) in Italian.