We investigate the convergence of infinite-centre Gibbons-Hawking metrics, in the contexts of four-dimensional gravitational instantons and their applications, Kaluza-Klein monopoles and vortices, gravitational calorons, analytical extensions of Majumdar-Papapetrou metrics to form extreme Reissner-Nordstrom black holes, and Kaluza-Klein black holes. We find that, in most cases, periodic arrangements of the sources give rise to divergent potentials. We investigate the consequences of various methods of ensuring convergence, particularly in terms of the appearance of naked singularities, and construct several new solutions of Einstein's equations.