In summary, the relative refractory period is a time in which the neuron can fire an action potential, but it needs a greater stimulus. During an action potential, voltage-gated sodium channels open to let in positive ions - sodium. These depolarize the cell.
On average, reciting five Mysteries of the Rosary typically takes about 15-20 minutes depending on whether the optional prayers are also recited. Additionally, some people may take longer than 20 minutes if they decide to devote extra time for reflection and meditation on any of the Mysteries.
Centering prayer, as taught by Fr. Basil Pennington and Fr. Thomas Keating, is a method of prayer that is supposed to lead a person into contemplation. It is supposed to be done for twenty minutes in the morning and twenty minutes in the evening.