vinayak chauhan
When you reduce the size of element, you are recommended to reduce the time step correspondingly. Hence you need to scale it down or up based on your mesh details for better results. Also time steps judge the number of iterations for convergence.
However if you are not changing the mesh size then a larger or smaller time step wont affect your convergence condition , hence you can increase your time step for doing the calculation fast , as it will decrease the number of iterations for calculation.

I hope it helps.