I did my 144 hours in 4 school years and 2 semesters. That's 14 semesters available, counting summer school. Had 5 co-op semesters, so 9 semesters in school, one of which was a summer. Did my entire freshman and senior years in school. 3 of the 5 co-op semesters were in the summer and I only had 1 summer at school.
In a normal semester, I took 18-19 hours but some classes had labs that didn't count as hours but you still had to take them. My senior last semester I only took a couple of courses.
Back then (and maybe now), the catalog laid out a curriculum for graduating in 4 years and it was very specific. There were very few electives in engineering ... I think the only 2 real ones were humanities (I took American Government and Psychology). There were a few technical electives, but they had to be in your major field so there weren't many options available. Also had to take ROTC the first 2 years that's not required any more. But that only counted for 1 hour per semester.
We also had classes that started at 7 a.m., and a few 5 hour classes that met M-F. And the majority of classes were MWF and TThS ... yes, Saturday. Saturday classes were the norm.