ok so each individual sound in a song can and most likely should be sidechained - with the option to automate this on or off easily via the redrum master volume knob. Here's how I set my tracks ambiguously speaking:
So lets say you have two kicks layered for the "KICK" -kick high and kick low - the percy/punch one needs to be up front in the mix - but the sub kick needs to drive the track - so light sidechaining CAN/COULD help with this, sometimes the samples work for it, sometimes not. This is just one trick but most sounds should be sidechained for electronic based music - helps eliminate need for limiters too which taint the overall sound, usually to the detriment of the final product. Same for snares/claps - most of the the layers are sdechained even when on the kicks - it creates a subtle ducking action with very subtle mclass sidechain params that helps move the pace of the track.
For bass lines, the typical bass line will be 3-5 sound sources - each with their own mclass sidechain connected to a redrum loaded with a kick (the fatter sub kick of the two for sake of wide sidechain mclass params) - so thats 3-5 diff mclass sidechain settings with 3-5 redrums and 3-5 synths which require slightly different mclass params for a good loopy sidechain. since each have slightly different settings they behave slightly different off the kick and this creates dynamic timbres that are pleasant and rich to the ear, helping create a sense of fullness in the headroom. And the easy way to eliminate the sidechain at a moments notice via automation is thru the master redrum vol knob - rather than automating the ratio and threshold settings, which cause a deterioration of the sound as you subtract the sidechain. plus its one vol auto versus at least two mclass autos - less cpu intensive when you have dozens of this going on.