I only take 1-2 courses each semester. Which means it'll take me a total of 3 years to graduate. Right now I'm about a year in, with 3 courses under my belt. One of the courses I took was time-consuming and difficult- maybe 15-20 hours a week. The other two however have been relatively easy, where I've spent less than 10 hours a week on each.
Adding to this, there's an informal course review site that gives you pretty good reviews from other students. It should give you some more context:
https://omscentral.com/reviews
