Simulations to improve teachers' professional conduct and development have recently increased globally. However, research on the impact on teachers at different professional stages is limited. The current study examined the effects of the simulations carried out at Tel Hai Academic College in the north of Israel in the Pre-service, Internship, and Professional teacher development phases to find their relative importance in the effect of the simulations on their participants and evaluate this teacher development practice. Four hundred thirty-seven teachers in three professional development phases participated in educational simulations and completed a questionnaire about three assessment levels of the individual (experience, learning, and application). Teachers perceived the most effective simulations in all parameters during their internship stage. Therefore, when simulations are used worldwide to advance professional teachers' development, it is recommended to do so as soon as possible upon entering the internship and first years' phase of teaching.