I've been hiring several developers from different places around the world. It all goes well, but I see that some of them are abusing my polite overlooking too much lately.

They are all hired for a full-day. However, I see that after 5 hours in a day, not much has been done.

I am considering to develop a software that will take a screenshot of the computer screen every 1-5 minutes and upload it to my system. However, this is going to the extremes.

How do people usually manage remote developers?