Signing of the new intermediates

Issuance Policy
6

The CRL is signed every 3 months it seems:

Certificate Revocation List (CRL):
        Version 2 (0x1)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: /C=US/O=Internet Security Research Group/CN=ISRG Root X1
        Last Update: Feb 23 12:00:00 2016 GMT
        Next Update: May 23 12:00:00 2016 GMT

So I guess that doesn’t matter with regard to the intermediate signing ceremony.