Okay... having made/designed PCBs and microchips for cell phone radio section power amplifiers (6 Watts for just under 2GHz or so including DC bias with leaky RF issues on the same traces)...
yes, right angles make a difference at these RF frequencies, and since we were pushing the envelope, the design was *VERY* touchy to the point where the division went out of business because we could not get it to go in 2 years time with some wacky technology that we were exploiting... These amplifiers must meet a spec for 10:1 VSWR (reflections and standing wave ratio stuff), because even with a fractal or patch antenna, the user is going to throw their cell phone into the metallic ash tray in the car or in their bag with a mylarised spent potato crisp bag or under their tin-foil hat
....
At audio frequencies maybe not so much... Although I always, when feasible, expect to carry audio and low frequency RF as necessary, such that stray or errant RF can be handled gracefully (whether emphasized on purpose, say with high-speed analog portions of a discrete A/D design before quantization with a latching high-speed comparator or for proper attenuation of any RF effects - depending on the circuit needs)... It really does not cost much more to be RF conscious during analog audio design....
Remember that if you want to faithfully reproduce a 20kHz square wave, the circuit needs to reproduce all the higher harmonics... Although I submit that this is not ideal or practical as folks might not be listening to music on high bandwidth reproduction equipment that has 20kHz square waves (even with digital stuff these days having the inability to reproduce harmonics for 11kHz square waves; although there may be other effects happening here in phase and reflection back into the audio domain)...
However, this is more important for digital circuits in "trying" to maintain a square wave at whatever high-speed digital frequencies and in fact it becomes an analog problem at high frequencies where the square wave is rounded over and might be ringing with all the stray inductances and capacitances on a microstrip style of trace.... And of course the FCC or other radio governing body might get involved with square wave harmonic hash being generated....
However, routing PCBs with angled traces is also ideal for routing topology and shorter traces in theory.... By definition a^2 + b^2 = c^2 and thusly a+b >> c where if the trace was diagonal rather than manhattan style (right angles) then it would be shorter....
For high voltage we were concerned about sharp corners in the microchip world, especially with VSWR stuff reflecting energy back into final stage transistors on GaAs and creating higher voltage standing waves... The same is true in the PCB world, as I have had a Fender Hot Rod Deville arc over on the PCB traces.... Copper threads can electrolytically "grow" to more sensitive high gain traces nearby....
Anyway.... sorry for the tome.....