If you want to earn those hours, load up your GPUs with as many WUs that will run without erroring out. The longer they run the better....
Code:
<app_config>
<project_max_concurrent>0</project_max_concurrent>
<app>
<name>opng</name>
<max_concurrent>2</max_concurrent>
<gpu_versions>
<gpu_usage>0.5</gpu_usage>
<cpu_usage>0.5</cpu_usage>
</gpu_versions>
</app>
</app_config>