The defined volume is the best option, especially at 5,000ft and 10nm at least. If you're on a local flight you often don't go above 5,000ft but may be anywhere under that. Anyone above 5,000ft is generally going somewhere. Way back in charter days I'd always plan between 7-10,000ft as it got you up out of the way.
Prescribed mandatory calls for taxi, entering runway, inbound and joining circuit are the way to go with a STANDARD FORMAT! Calling every leg of the circuit is rediculous. Make the required mandatory calls and only if needed make more as required.
Use a bit of common sense in regard to inbound calls. Jets/turboprops are monitoring the CTAF (NTA) from a long way out. Faster aircraft call further out as arrival time will be similar to someone closer but slower.
As for the volume of space, a jet/turboprop will usually be at 5-6,000ft 20nm out and 3,000ft at 10nm.