macuser_22 is correct. "Periodic payments" refers to distributions being received in the form of an annuity (a traditional pension, for example), where your distribution amounts and dates are all predetermined. What you are receiving are nonperiodic distributions, even though some amounts are required to be distributed each year. If you have the freedom to take out more than the RMD, it's nonperiodic, even if by choice you take the same amount out each time on a regular schedule. The Simplified Method and General Rule are applicable only to periodic payments being received in the form of an annuity.
