Limitations to simulations
Assumptions made regarding variables might not be true, e.g. the distribution of supposedly normally distributed data may not be quite normal. (Have a back-up analysis plan!)
Parameter space may be unknown. (Explore it a bit and use previous observations to be at least in a relevant range.)
Computational resources and time. (Use research software engineer staff on campus to optimize code, use parallel core processing, use server services on campus, etc.)
Simulations might be redundant with mathematical demonstrations. (I don’t mind, still useful for me!)