For various gain clone-like circuits it is noted that you should use an as short as possible feedback loop to prevent oscillation. In my case I have an LM1875 (20W AUDIO POWER AMPLIFIER DATASHEET)and the application note suggests to put some filter capacitors as close as possible to the supply pins. When I do this I get an awkward PCB layout but when I look at the example layout in the application note the designer was pretty lenient about the 'as close as possible' bit yielding an overall much nicer looking layout.

Is the oscillation mechanism that is to be prevented in the feedback loop and near the supply pins the same? Is it caused by the trace capacitance and/or impedance or something different? I'm interested in a formula that roughly models this effect so I can get a feel for what happens with for example trace lengths of 1, 10, 100 mm respectively.