Systems and methods include, responsive to a request for capacity change of X channels, X is an integer >1, on an optical section (14) and at an Optical Add/Drop Multiplexer (OADM) node (12) in an optical network (10), dividing optical spectrum on the optical section into M slots, M is an integer >1, such that the capacity change of X channels takes a maximum of N steps, N is an integer >1; and performing the capacity change of X channels in up to the N steps in an interleaved manner that changes a subset of the X channels in each of the N steps. For each step, the performing can include a maximum of M/N slots of the M slots with spacing between each of the M/N slots not used for the capacity change in a corresponding step. The spacing can be f, (N+f), (2N+f), . . . , M over the optical spectrum, where f is each step, f=1, 2, . . . , N.