I can't remember how buffers in DOS work, but that page seems to indicate that for input purposes they're used as some kind of a read-ahead buffer. That doesn't sound quite the same as keeping recently or commonly accessed data in RAM to speed repeated access.
DOS did have SmartDrive [1], though, which IIRC provided a more typical disk cache. I wouldn't think it was loaded in the default configuration, though I'm not sure.
As said in that page and the documentation, the read-ahead is the [,X] part, which is actually disabled by default in every DOS past 6.x (incl FreeDOS). The first part is the number of primary buffers which is indeed "for keeping recently read data in RAM".
Smartdrv, like Fastopen, just allows disk buffers to survive a Close File call. Normally DOS only does close-to-open consistency i.e. buffers are flushed on close. Smartdrv specifically also allows write-back rather than write-through.
And, anyway: yes, Smartdrv is enabled by default in 6.x installs with enough memory.
Nice, although if it is set to 15, that's only 7,680 bytes of buffer, and even 99 is just 50,688 bytes. It's not loading now, but I suspect a single load of all those images will flush that data
