What Zidane has done was once what will never happen again probably. 
He got lucky on many levels and I think he knows it and that is why he doesn't return to the business because he would be measured by what he has done on the past and he knows it can't be done again.
He got lucky on many levels and I think he knows it and that is why he doesn't return to the business because he would be measured by what he has done on the past and he knows it can't be done again.
We could say that, he got lucky and that would be acceptable when he did it once, getting lucky in a first attempt but, it’s not exactly luck when you were able to repeat it through several seasons and consecutively which was what he did.
It’s a matter of having the right combination of players, playing at such an elite level, an elite team, having the necessary resources and knowing how to use these players. Zidane had the means in Real Madrid and was able to use it.
Best thing he did was left while he was still a knight in shining armor. His likely not going to be able to repeat it though.
When he returned to Real Madrid from 2019 - 2021, he won nothing except for the La Liga championship in 2020.
Of course the combination of players is the most important issue when a team thrives for success, but luck plays a role too, especially in a competition like the Champions League. If it was just about being the best team, then Manchester City would have won the trophy a couple of times by now, but they could only get it done once. When Zidane was Real madrid's coach, it was so many last second goals, several balls got luckily deflected and became goals. If that luck is not on your side, winning the Champions League is almost impossible in my opinion.