Evolution of spindle during mitosis relies on the stochastic capture of microtubules at kinetochores. Kinetochore texture is a crucial factor of the efficiency and fidelity of this process with large kinetochores expected to speed up assembly at the cost of accuracy, and smaller kinetochores to suppress errors at the expense of efficiency. We show that at the onset of mitosis kinetochores form large crescent structures that subsequently condense into discrete objects on opposite sides of the centromere. This condensation occurs only after the formation of end-on microtubule attachments. In silico modelling of kinetochore expansion-compaction in the context of lateral interactions correctly predict experimentally-observed spindle assembly times with reasonable error rates. The computational model suggests that larger kinetochores reduce both errors and assembly times, explaining the robustness of spindle morphogenesis and the functional significance of augmented kinetochores.