1. A computer-implemented method comprising: receiving model data from a subset of enterprise users associated with a multi-level enterprise hierarchy that includes a plurality of hierarchically arranged nodes, wherein the model data defines, for at least a group of nodes in the plurality of hierarchically arranged nodes, two or more sub-models that collectively define a set of sub-nodes for the group of nodes, wherein the two or more sub-models are associated with different planning activities, wherein each particular node in the group of nodes includes two or more of its own sub-nodes corresponding to the different planning activities, wherein each particular node in the group of nodes and its corresponding two or more sub-nodes are located in the same level of the multi-level enterprise hierarchy, and wherein each sub-node of any particular node in the group of nodes is associated with a different one of the different planning activities; combining, by at least one computer, the two or more sub-models defined by the model data to obtain a single enterprise planning model that incorporates the different planning activities associated with the two or more sub-models; and executing, by the at least one computer, one enterprise planning session in accordance with the obtained enterprise planning model, wherein executing the one enterprise planning session includes: receiving contribution data from enterprise users associated with sub-nodes of a node in the group of nodes, wherein the node and the sub-nodes of the node are collectively located in a first level that is higher than a lowest level of the multi-level enterprise hierarchy, wherein the received contribution data represents contribution data for each of the different planning activities of the two or more sub-models, and wherein the sub-nodes of the node are each associated with a different one of the different planning activities; aggregating the received contribution data such that the received contribution data of the different planning activities is combined; and reconciling the aggregated contribution data for the different planning activities for the node in the first level with target data that combines targets for the different planning activities for the node.