What are the advantages of squawking 7700? I was reading this question about how do pilots send distress signals in emergency scenarios, and that got me thinking...

In voretaq7's answer, he states that there are three ways to send distress signals, one of them is by the aircraft's transponder


  Three transponder codes are reserved for unusual/emergency situations:
   - 7700 for general emergencies.
   - 7600 for loss of communication    (radio failure).
   -  7500 for hijacking or other unlawful    interference.


I can understand the reason to squawk both 7500 and 7600 in the appropriate situation, but I'm failing to understand why squawk 7700 in an emergency scenario.

So that's what I'm thinking:


In case of a hijack, the ability to squawk 7500 to silent alert the ATC of the situation, without the hijacker knowing, is an advantage. 
In case of a radio failure, where you can't alert the ATC over the radio, the ability to squawk 7600 and make them aware of your situation, is an advantage.
In case of emergency, where the pilots are trying to handle a lot of things (high workload scenario), to stop everything to configure the aircraft's transponder, when they are communicating with the ATC by radio, doesn't seem like a good thing to do.


So, finally, here are my questions:


Is it common for pilots to squawk 7700 in emergency scenarios?
What are the advantages, for the pilots, to squawk 7700 in emergencies situations?
If you make a radio call, unless you are on 121.5 (or 243 military), then only the station you are talking to will initially know about the emergency. Initial calls should always be with the unit you are working with unless you are VFR.

If you squawk 7700, then all stations in transponder range, including possible airborne stations such as AWACS and SAR will know right away that you are in trouble, with position, altitude and possibly aircraft type and flight number.

If VFR, you might not be talking to anyone and may not have the frequencies of nearby units easily to hand.

Squawking 7700 is definitely a good thing.

You mentioned being busy.  The mantra drilled into everyone is "aviate, navigate, communicate".  In most circumstances, fly the plane, fly it where you want it to go, then tell someone about it.  Squawking 7700 will be one of the last actions carried out.