Fisbang, I think most pilots understand how busy an ATCO can be and how rapidly workload can increase to an almost impossible level.
From a mere pilots perspective, it's more helpful if a pilot gets advance warning that a handover may not be possible due to controller workload and that a free call will be necessary.
It occasionally happens that a controller, out of the best of intentions, hangs on" to an aircraft a little too long. The pilot is becoming increasingly aware that he needs to obtain a clearance in short order but can't just leave the present frequency, having been told to stand by. But if he carries on regardless he will bust airspace so must take action ASAP.
The lesson for pilots is to have plan B already thought out. It's not the end of the world to reduce speed and/or put in an ad hoc holding pattern.