Where is the Best Place for Cron Methods ?

Hi, i've a cron controller that calls its own methods. Pretty common. Now : these methods calls others methods like clean old entry from others coltroller/model processes. These others methods:

1. not requires authentication
   
2. not requires views (obviously)
   

So, Where is the Best Place for these methods ?

1. Cron Controller
   
2. Parent's methods controllers
   
3. involved models
   

which ones ?
thanks