The user may choose to use one of the two approaches,
a) the implicit based solution and switches to explicit as necessary;
b) the explicit based solution and switches to implicit as necessary;
The common challenge for using the implicit method is to get a converged solution. When there is a convergence problem, it is better to switch to explicit temporarily to overcome the difficulty.
The dynamic effect in the explicit method may become too large and negatively affect the simulation results. It is better to switch to implicit temporarily to reduce the dynamic effect and correct the error.