Complex sentence: During the period when Stu Hart was regularly training individuals at the school it held a reputation for being one of the harshest wrestling schools in the world and graduating from it was considered very impresive and something which would be brought up on air on televised wrestling shows.
Split into simpler sentences: During the period when Stu Hart was regularly training individuals at the school, it held a reputation for being one of the harshest wrestling schools in the world. Graduating from it was considered very impressive and something which would be brought up on air on televised wrestling shows.