Start by getting rid of the
convert(varchar, SOME DATE, 1)
statements - there are much better ways to compare two
values whilst ignoring the time part.
In this case, you want to know whether the difference between the action date and the current date is a multiple of 3 days. For that, you'll want to use the modulus operator:
% (Modulus) (Transact-SQL) - SQL Server | Microsoft Learn
... and (DateDiff(day, ACTION_DATE, GetDate()) % 3) = 0 ...