There is a Site Option for Smat History, to set a maximum age of Smat files. This is in version 19.1; don’t remember if this was in 6.2.
I think, but have not tested, that this age limit applies to files in the /process/SmatHistory folder, not the /process folder. If so, then this should meet your needs.
I’m reviewing these settings. There’s the option for log history and automatic log cycling. Do these both need to be set? Also, I’ve noticed that inside the smat databases folder there are now .old.smatdb with .smatdb. Why are there both?