There are other side channels where an attacker cannot cause the desired operation to be repeated thousands or millions of times back-to-back..
If Alice performs an operation only once, and it leaks sensitive data through a timing variation of 100-200ns, Mallory is in great shape with a 1ns clock source and in pretty awful shape with a 10us one.
If Alice performs an operation only once, and it leaks sensitive data through a timing variation of 100-200ns, Mallory is in great shape with a 1ns clock source and in pretty awful shape with a 10us one.