When I first wrote this (early 90's) the predicted time of an occultation event wasn't as good as it is now so I made the time of simulated event vary between several seconds and several minutes. Although the simulated starfeild is different each time, the "star" which dims will always be the center "star".
For that reason I wrote this little simulator program. Practice does produce consistency of reaction, and I've continued to find the simulator useful since it's natural to get "rusty" from not doing a particular task frequently.
AOPS.exe is a little (51k) DOS utility that should run on any PC type machine. It only takes a few practice runs to "oil" one's reaction before making an actual observation attempt.