At what point is filling doubles two fills?

[Bubblemaker]

I would say one fill, But running a shop once myself air is free its the process in which your paying for. But since most people run Isolators here you can fill both cylinders with one whip independent doubles I would say two fills.

I would also agree with Jon in that the compressor is being worked harder at the end of the fill. Usually you have to replace your high end stage more often then your lower end ones.

K