How much time does a university typically give a professor to draft a syllabus and how long before they are approved? I was wondering about the process of accepting a syllabus, and if it was different for the Humanities and in the Sciences.  Suppose, just so the question is less abstract, there is a new software program that helps research, and a professor wants to add it to a syllabus.  Would he/she need to get approval from the department chair?  How long do changes/updates to a syllabus usually take in a US University?

Let's take for example an Introduction to Literature class, and typically there are six texts in the course.  A professor wants to exchange one of the texts for another one.  What would be the process of getting that done?  Would there be endless meetings or could the professor simply add the text.  Who would need to approve this sort of change in the syllabus?  

Or let's take a Science class.  There are always advances in science.  How long does it take for a syllabus to change to include updated texts?
Academic freedom means instructors can choose the material they teach.  Professor are loosely bound by the course calendar - if you are assigned a course on Greek drama and you teach instead Latin drama you may be reassigned - but otherwise you’re largely on your own: you can choose the Greek dramas to be studied in your course.

If the material is repeatedly too hard (high fail rate) then the Dean (usually in consultation with the chair) may reassign you but in a functioning unit some collegiality will usually resolve such issues, and will efficiently link courses in a pre-requisite chain.

There is usually an administrative procedure to make substantial changes to a calendar entry for a course.  Where I work it takes 2-3 months, mostly because the appropriate meetings (which must be done in a specific sequence) are rarely held “on the spot”.  The change is approved by the department, then by the Faculty, then scrutinized by some academic committee for justifications, additional resources etc, and if approved then onwards to Senate for final approval.

Completely new courses are usually tested out as “special topic” for,one or two years  to see what works and what doesn’t work.