Earned hours calculation

Does anyone understand how the earned hours are calculated in job details? I have a scenario where 3 SKUs are produced at the same time so the crew size is .33. It appears that the earned hours and earned cost ignore this crew size. If they standard is 100 per hour for each part and they produce 100 of each it calculates earned hours as 3 hours. It looks like I would need to triple my standard rate to have it calculate one earned hour. I also think it uses this same calculation to determine resource group efficiencies.

Thanks for your help.