In case of typical service time processes it is shown for queueing system M/G/1 that the optimal strategy SRPT (Shortest Remainig Processing Time first) offers, compared to other strategies like FIFO and PS (Processor Sharing), not only the well known favorable mean value TDBAR but also a low variance sigma2{TD} of the delay time TD. Due to these advantages SRPT can be recommanded for practical applications in communication networks. - The present investigation includes the strategy SPT (Shortest Processing Time first), whose properties correspond to SRPT in case of non-preemptive strategies.