I take your point when descending at 2000 ft a minute wanting to call 1 minute before having to level off, but if you consider that there are times I have 10 aircraft all converging at the arrival fix all assigned varying interim levels if they all call "approaching" their level 1 minute before they reach it, it has a snowball effect and I never get a chance to assign descent to anyone.
Sorry but I have a radar and can see what level you are at and if I'm busy last thing I need when trying to assign someone descent or turn them is you overtransmitting telling me what I already know but have put to the back of the priority queue. If the frequency is quiet fill your boots and tell me you are approaching.
One thing I would like to thank Aussie pilots for is that they always advise there level maintaining, or assigned level on first contact. I've been amazed overseas to find at least half of the pilots flying through the middle east have an initial call with just the calsign and nothing else, meaning you have to make an extra transmission (and so do they) to get their level out of them.