Basic Expression Q

[David Tarr <dltarr(at)gmail.com>]

I have a logo that I'm moving around using a random custom (RAND) _expression_. I like the move, but it's moving around with too much frequency.  It moves every frame, when I would rather have it move about five times per second (and have the moves last until the next random move comes in).  I'm probably missing something obvious, but is there a standard way to control time with the DS expressions?  Thanks for your help.