Since Ferguson's retirement, David Moyes, Louis van Gaal, José Mourinho, Ole Gunnar Solskjaer and Erik ten Hag have occupied the position.
Now the now 82-year-old Scot has spoken about the demands.
"I was lucky to have a period at United where I was manager and had control over most of the club," he said on the The Go Radio Business Show.
"It was about me taking that responsibility and also - which was very important - that I had the personality and communication skills to handle it.
"It is very important if you are going to coach a club of Manchester United's size: You have to have a good personality, and you have to be really skilled when it comes to organization and being able to handle different types of players.
"In addition, you must be aware that you must not only deliver for your players, but also for a huge supporter base."