The 52-year-old, Sbragia, replaced Roy Keane as Black Cats boss three weeks ago.
He said: “Managing in the Premier League has become more frenetic since I took over at Everton nearly seven years ago.
“We’re coming into an era of football where it is going to be a short-term job.
“The days of managing a club for the length of period Alex Ferguson and Arsene Wenger have are maybe gone.
“When you come into management these days you are going to have to accept that you might only be in a job eight months, 12 months or 18 months.
“I’ve been fortunate, but some managers don’t always have the best support of their chairman.
“This is the world of football management today.”