Root canal treatment should take as long as necessary to do it right. Depending on the tooth, number of roots and canals, extent of the infection, general anatomy (curved, twisted, straight), if the canals appear open or calcified (totally obliterated/blocked out), 1st root canal or a retreatment of a failed root canal....the list goes on. Sometimes it can be done in one visit and sometimes multiple visits. As I say, do it right the first time so you don't have to do it over. 25% (roughly) of my practice I am retreating someone else's work...and I am asked "doc, why does it take 4 visits to redo the root canal? The guy who did it the first time was done in 1/2 an hour." Never time to do it right the first time, so you have to do it over. I would be glad to tell you how many visits it took to treat once we are done, but sadly, I cannot say how many it will take. Your endodontist can deal with more complicated cases easier than a non-specialist and so they should be done quicker...unless they see complications and issues that would be missed by a non-specialist and will take their time to treat it correctly.