We study the dynamic phase diagram of a spin model associated with the Number Partitioning Problem, as a function of temperature and of the fraction K/N of spins allowed to flip simultaneously. The case K = 1 reproduces the activated behavior of Bouchaud's trap model, whereas the opposite limit K = N can be mapped onto the entropic trap model proposed by Barrat and Mézard. In the intermediate case 1 ≪ K ≪ N , the dynamics corresponds to a modified version of the Barrat and Mézard model, which includes a slow (rather than instantaneous) decorrelation at each step. A transition from an activated regime to an entropic one is observed at temperature Tg/2 in agreement with recent work on this model. Ergodicity breaking occurs for T < Tg/2 in the thermodynamic limit, if K/N → 0. In this temperature range, the model exhibits a non trivial fluctuation-dissipation relation leading for K ≪ N to a single effective temperature equal to Tg/2. These results give new insights on the relevance and limitations of the picture proposed by simple trap models.