I am assuming you are using ASME B31.3.
Number of cycles does not apply to sustained cases, unless you want to consider fluctuation of pressure as a cyclic event.
I guess it is one piping system that you are dealing with so, logically it should have one governing set of allowable stresses.
If you have different numbers of cycles associated with several expansion cases, the allowable displacement stress range should be derived from B31.3 section 302.3.5 (equation 1d).