The Spectrometric Oil Analysis can can detect particle size only upto 5 microns, where as the wear particle size distribution for any industrial machine is 5 to 60 microns.
hence, is it mandatory to have this test included in a Lube Oil analysis program?
I understand that above test is always recommended to be included in a lube oil analysis program?

Yes Spectrometric Oil Analysis via ICP is very useful to have as part of a lube analysis program. We see many samples from industrial machines and this test is a good indicator of wear trends in these machines. It is important to remember that this test not only measures wear elements but contamination levels, (eg. Si), and oil additive levels also (eg. Ca, S, P, Zn, Mg). You should however also include another test to ensure you can detect larger particles missed by the Spectrometric (ICP) test. For example particle count, Particle Quantifier, visual debris filter pad etc. Most wear modes begin with fine wear particles detectable by ICP and only progress to larger particles undetectable by ICP once the wear mode has progressed. It is therefore important to understand the workings of the Spectrometric instrument in order to correctly interpret the results.