Yes! The test result may vary widely depending on the physical setup. In addition, there could be some logical errors in the codes that can only be detected through a long time test. My setup of Post-40 intially worked for few seconds and then hanged. I was lucky to observe that the the fault repeated. I discovered through physical scanning of the sketch that at the Master side, there was no code to reset the array index after the 1st pass. I corrected the error and then the sketch started normal functioning.
As the @muhit114474 is reporting that his system hangs working for a while, he is advised to scrutinize his sketches if there are any logical errors.