Sen. Grassley said on C-SPAN this morning that today each senator gets 30 min., tomorrow they get 20 min..
On Thurs., I believe the "witnesses" get their time, then to go back to senators' questions. If necessary, they will go through the weekend. It doesn't end until every senator has asked all of his/her questions.
At the end of this hearing, D.C. will end up containing the biggest pile of excrement known to man.