You don't use N2 for descents with A/I on?
-mini
Depends on the flavor of CRJ you're flying. on some CRJs, you'll get the arc and it's up to you to make sure you get the thrust setting above the arc otherwise you may get the anti-ice caution. on other CRJs, the FADEC reschedules the flight idle thrust to a higher setting in attempt to keep the bleed temps up.
Flight regime, case 1. Lose power, increase angle of attack to bleed airspeed quickly while maintaining altitude.
Flight regime case 2. "Large power changes" during approach/intercepting glide path.
Flight regime, case 3: having fun.
I think it's a function of how well you know your aircraft. Just getting into a type, all you know is what you've learned in the simulator, but it doesn't translate well into real-world line flying. As you fly, you get a better feel of what the aircraft's actual capabilties are and what you are comfortable doing.
Case 1 - I misunderstood the original case - as the scenario I had in mind was going into a certain west-coast city from the mid-west, LA Center usually keeps us high - like FL240 40 miles from the airport, then gives us an "expedite to 9,000ft, altimeter 29xx" after crossing a certain VOR. Usually the technique I saw and started using was as we get close to the TOD is to slow to about 230kts, then VS down to 5500ft/min or 6000ft/min and deploy the flight spoilers - we end up accelerating to 330kts in the dive, but by the time you start levelling off to capture 9,000ft, the speed bleeds off to below 250kts and you have to add power in. Otherwise, you'd just get vectored around in a circle to get you down for approach.
But to slow down, usually I'll try to plan a level segment somewhere in the descent. I think that's a pretty normal thing.
Case 3 - I think it goes back to how comfortable are you with the aircraft.