A method comprising: responsive to a request for capacity change of X channels of an optical spectrum on an optical section and at an Optical Add/Drop Multiplexer, OADM, node in an optical network, dividing usable optical spectrum of the optical spectrum into M slots to satisfy the capacity change of the X channels, each slot including one channel or multiple adjacent channels of the optical spectrum, and separating the M slots into N distinct bundles, each bundle including a subset of the slots dispersed throughout the optical spectrum, where X is an integer > 1, M is an integer > 1, and N is an integer > 1; and performing the capacity change of the N bundles in N sequential steps, the capacity change in each step including simultaneously performing capacity change for the subset of slots in each bundle characterized in that the performing includes a maximum of M/N slots of the M slots in each of the N sequential steps by interleaving bundling and wherein 1) the capacity change includes any of adding channels by replacing channel holders and removing channels by adding channel holders, or 2) some or all of the M slots have equal or unequal bandwidth, and bandwidth of some or all of the M slots is dynamically adjustable based on the capacity change handled on that step, or 3) a given channel of the X channels is assigned a corresponding capacity change in a given step when the given channel falls partially or fully within a given slot for the given step, or 4) the performing the capacity change is performed, when power is known to be available at a multiplexer input using locally monitored points, without coordination and communication with other OADM nodes in the optical network, or 5) if a capacity change is not requested for one of the M slots, optical signals or channel holders on that slot remain uninterrupted during the capacity change. responsive to a request for capacity change of X channels of an optical spectrum on an optical section and at an Optical Add/Drop Multiplexer, OADM, node in an optical network, dividing usable optical spectrum of the optical spectrum into M slots to satisfy the capacity change of the X channels, each slot including one channel or multiple adjacent channels of the optical spectrum, and separating the M slots into N distinct bundles, each bundle including a subset of the slots dispersed throughout the optical spectrum, where X is an integer > 1, M is an integer > 1, and N is an integer > 1; and performing the capacity change of the N bundles in N sequential steps, the capacity change in each step including simultaneously performing capacity change for the subset of slots in each bundle characterized in that the performing includes a maximum of M/N slots of the M slots in each of the N sequential steps by interleaving bundling and wherein 1) the capacity change includes any of adding channels by replacing channel holders and removing channels by adding channel holders, or 2) some or all of the M slots have equal or unequal bandwidth, and bandwidth of some or all of the M slots is dynamically adjustable based on the capacity change handled on that step, or 3) a given channel of the X channels is assigned a corresponding capacity change in a given step when the given channel falls partially or fully within a given slot for the given step, or 4) the performing the capacity change is performed, when power is known to be available at a multiplexer input using locally monitored points, without coordination and communication with other OADM nodes in the optical network, or 5) if a capacity change is not requested for one of the M slots, optical signals or channel holders on that slot remain uninterrupted during the capacity change. 1) the capacity change includes any of adding channels by replacing channel holders and removing channels by adding channel holders, or 2) some or all of the M slots have equal or unequal bandwidth, and bandwidth of some or all of the M slots is dynamically adjustable based on the capacity change handled on that step, or 3) a given channel of the X channels is assigned a corresponding capacity change in a given step when the given channel falls partially or fully within a given slot for the given step, or 4) the performing the capacity change is performed, when power is known to be available at a multiplexer input using locally monitored points, without coordination and communication with other OADM nodes in the optical network, or 5) if a capacity change is not requested for one of the M slots, optical signals or channel holders on that slot remain uninterrupted during the capacity change.