Not so much a pit, actually, as a big pile of sand spread out for a gelanggang–a circular workout area. It tends to creep down the slope toward the chicken yard and needs be shoveled back uphill, but it makes for a nice slow-your-feet-down training surface.
Churning in ankle-deep sand is not the same as moving on dry ground or a nice concrete garage floor. If you need lightning foot-speed to make a technique work, you need a workaround, 'cause it isn't happening there.
Of course, falling onto sand is somewhat softer than the concrete. Then again, dropping onto a knee repeatedly to practice shoots for single- or double-leg takedowns, and then being tossed by the defender hither and yon for continued groundwork does involve some abrasive action to one's bare skin.
Note to self: Don't wear shorts to class in the sand. Those sand burns take longer to scab over and heal than they used to take ...