@rebelprof I wonder if you are making efficient use of the "import content" function. When you import content, you have a few choices to make.
First, you can import "selected" content or "all content." I would recommend that you choose the former option. You can choose which items to import. That might save you a lot of time.
Second, make sure that you "remove" the dates when you import content from the old course into the new course shell. Then you can easily set up dates in the new course shell by clicking on "Assignments" in the course navigation bar. Then click on the three dots in the upper righthand corner. From their select "Edit Assignment Dates."
Lastly, keep the content in your course "evergreen" by not adding specific dates to the titles or within the content. For example, label your modules "Week 1, Week 2,......" You can write "This assignment is due on Thursday" without giving the specific calendar date. You can save many hours this way.