This method of installation does require some planning to be successful.
The coils of tubing are 500 ft. long. The heating loops can be up to 500 ft long but they should not exceed 500 ft. Any loop more than 520 ft. will greatly effect flow and heat output.                             
   Solid blocking between joists does effect your method of installation.
A better choice is cross bracing.
   If you will make up a rough sketch before you start it will be a great help.
   You will need to know the number of joist spaces and the length of   
the spaces between blocking.

This system is designed to furnish more heat than is truly needed. With this fact in mind, if you simply spread the tubing  out as evenly as possible you can not go wrong. Concentrating the tubing slightly under bath rooms and areas of high heat loss adds to the overall comfort.

If you take 500 times the number of rolls of tubing designated for this floor and divide that by the length of the joist space, this will give you the number of single runs you can install. If the number of single runs exceeds the number of spaces, this number represents the number of doubles you can run.    Be sure to allow extra for the run to the manifold.