Hi ususer,

I'm afraid the contours don't work that way. If you assigned the resource at 50% and use a contour, Project will not increase the assignment units above the 50% -- therefore it has to increase the duration to spread the same amount of work over lower assignment units.

You can set the task up as fixed duration -- but in that case, the total amount of work will decrease with the max per day at 4 hours.

You can certainly contour the work manually in the task usage or resource usage view.

I hope this helps.

Julie