Queueing analysis can be useful in

Queueing analysis can be useful in comparing scheduling algorithms, but it also has limitations.
At the moment, the classes of algorithms and distributions that can be handled are fairly limited.
The mathematics of complicated algorithms and distributions can be difficult to work with. Thus,
arrival and service distributions are often defined in mathematically tractable but unrealistic—ways.
It is also generally necessary to make a number of independent assumptions, which may not be accurate.
As a result of these difficulties, queueing models are often only approximations of real systems, and the accuracy of the computed results may be questionable.