For a screening program to be effective, it must be timely and current. It does no good to screen someone AFTER they commit a transgression! That's the proverbial "closing the barn door after the horse has alrady escaped."
Since the screening questions you are expected to ask are "time-based" it's possible for someone to answer "NO" to a question today, but not be able to answer "NO" a week later - in other words, things happen.
So to keep up on such things, the DEA expects the registrant to "continually screen" employees that are granted access. That doesn't mean you have to ask them every day, but id does mean that you can't ask someone those questions once then never do it again even if they are employed for 20 years!
Although there is no specified interval or formal process for such a "continuous" screening program, here's what I think works best...Every time the registrant renews the DEA registration - every 3 years - the registrant repeats the screening of those to whom he/she has granted access. So when the renewal form is submitted, all of the folks on the Access Log are given a new screening questionnaire to complete. Simple, but it shows that the registrant is on top of things. Sure, people can lie, but at least the registrant can't be accused of not asking!
Completion of a simple screening questionnaire is adequate for most veterinary hospital staff. We've made it easy for you by sharing the screening questionnaire from The Complete Veterinary Practice Controlling Controlled Drugs Manual.
Here's a link to a FREE copy of the questionnaire:
https://www.safetyvet.com/images/EmployeeScreeningQuestionnaire.docx