The answer varies, depending on where you live, and which Scottish Rite you petition (apply for). Once you are a Master Mason, you are free to make application to the Ancient Accepted Scottish Rite of Freemasonry. In the USA, there are two jurisdictions: The Northern jurisdiction, which is all of the states north of the Ohio river, and East of the Mississippi. The Southern Jurisdiction comprises the remaining states, south of the Ohio, and west of the Mississippi, including Washington DC.
Each individual Scottish Rite group is called a "Valley". I belong to the Alexandria VA valley. I took the degrees of the Scottish Rite, in 1988. I took them on two successive Saturdays. I arrived at the building at 0800am Saturday morning, and stayed until 6pm that night. I went back the next Saturday, and completed the remainder of the program. At 6pm, I was a 32d degree Scottish Rite Mason (Sublime Prince of the Royal Secret).
In some locations (like Norfolk VA) you can take the entire Scottish Rite experience in one day. You arrive at 0600am, and at 6pm, you are completed.
As for the Shrine, The ceremonial takes about 45 minutes, depending on the particular Shrine center, where you make application. IN Columbus Ohio, the Shrine does a play, with songs and music, and a pyro-technic display. The Shrine initiation ceremony is short (45 minutes), but the extra features make it more entertaining. The ceremonial lasts about 7 hours, including meals, and the extra performances.
In Norfolk VA, the entire Shrine ceremony was over in 30 minutes.
You can learn more about the Scottish Rite and Shrine at:
Scottish Rite Freemasonry - Welcome to the Supreme Council, 33°, Ancient & Accepted Scottish Rite, Southern Jurisdiction, USA
and
Shriners - Welcome.
Or you may PM me directly, if you have any questions!