1. A computer implemented method of optimizing systems usage, the computer implemented method comprising: a processor receiving a work request; the processor decomposing the work request into units of work; the processor retrieving a first unit of work from the units of work; the processor selectively sending the first unit of work to a first system or a second system for execution based on a first work constraint on the first unit of work, wherein the first work constraint limits execution of the first unit of work to a system that is compliant with an execution environment rule for the first unit of work; and the processor minimizing a cost of running multiple units of work according to an algorithm: Minimize ⁢ ∑ i = 1 m ⁢ ∑ j = 1 u ⁢ H i , j * D i , j * P j where: u=a quantity of units of work to be executed, m=a quantity of machines available to a specific cloud computer system, H i,j =a run time in hours for each unit of work i on each machine j, D i,j =a dispatch of said each unit of work i on said each machine j, and P j =a cost hour for using said each machine j.