Auto-Adjust Activity Level of Resources

Hi. I have just downloaded the trial and run into an issue with the levelling of resources. A very simple example. I have two tasks (both 1 day effort) and one resource. Task 1 has fixed duration of two days and thus needs 50% effort. What happens is that Task 2 is carried out after Task 1 and Resource 1 is half-idle while completing Task 1. Now, the issue is that my tasks are flexible and Resource 1 should start working 50% on Task 2 while working on Task 1. As an effect, Resource 1 could finish both tasks in 2 days instead of 3.

Is there a way of having OP automatically using resources to their full availability even if this means changing activity levels on assigned tasks? If not, OP is very useful for me because I constantly have idling resources and completely off end dates for my project.
Thank you for any hints on this.
Best, Aurel