IMO, it depends on the cartridge. My experience with various cartridges is between 20 and 200 hours to reach best performance.
ALSO, at least in the case of an AT OC9/(all of them), if they sit idle for a while (week or more), it may take them a few record sides to get back to optimum. Regular play keeps them loose.
ALSO, at least in the case of an AT OC9/(all of them), if they sit idle for a while (week or more), it may take them a few record sides to get back to optimum. Regular play keeps them loose.