Structuring a big course - One story and 60 scenes or 60 stories?

I'm authoring quite a big language course for my community at http://talkirish.com.We'd previously designed a course using Captivate, and created 60 lessons which we hosted individually on the website.

I'm currently redesigning the course in Storyline (easier to use, HTML5 output being key drivers).I find designing each lesson simple, but cannot figure out which of the following two options would be my best choice:

Designing one 'story' with 60 'scenes' - so the learner launches and uses a single course with the 60 lessons inside.

OR

Doing as we did with Captivate - design 60 individual lessons and publish each of these on a homepage on our site, so the learner launches them individually.

The course is long - about 30 hours in total. It contains a lot of graphics and audio, so each individual lesson is about 5mb.

For updating and republishing the course, I can see big advantages in having a single HUGE course file. However, I'd rather create the course that's most usable for the learner.

We're implementing basic progress tracking (just in progress/complete) - should that be a factor in deciding on course format?

I welcome all advice