In MLB, there is no rule about the number of consecutive innings a pitcher can pitch.
There is no limit in regards to how many innings a Starting Pitcher must pitch in the Major League Baseball All Star game, a team can be winning and the Starting Pitcher could pitch only 2 innings but because All Star games have different rules, they can be given the Win.
In a Major League Baseball game, Starting Pitchers can pitch as many innings as needed, it is up to the discretion of his Manager however Starting Pitchers must pitch 5 innings in order to qualify for a win.
He must pitch a minimum of 5 complete innings.
10 innings in 3 days
I am in little league and so I know a little about this. I'll say on average we pitch about 60 pitches. Not that many, but a lot in just six innings.
As many as he can in a game before his couch takes him out