Help Understanding How PID Functions

So I understand that PID helps turn the temperature of your hot end and keeping it consistent. But when you run the gcode you specify a specific temperature, correct? Does this mean printing anything that isn’t that temperature won’t turn out well?For example, if I tune it for PLA at 205 then want to run some Nylon at 260 will the PID need to be retuned EVERY time I switch filaments?How does the printer do it without tuning PID? I can change filaments now and just adjust the temperature.I feel like I am missing something on how PID tuning works. Could someone help me out? Thanks!10.0.0.0.1 192.168.1.254 hotmail.com

On my machine and the Marlin it runs on, I run a auto tune with a cold extruder. It heats to the temp it needs and does it's thing and gives me an output I use as the input for M301. I save that with M500 and the hot end is tuned correctly to maintain a steady temperature no matter what it is set to. This M301 setting is tied to a hot end. I have 4 hot ends one with a different nozzle size each. I have all the PID setting stored in a spread sheet so I just enter the correct string when I switch hot ends. So you tune it once and you are done. If you notice the temp swinging a lot when printing, it may need to be retuned to compensate for heater ageing.
Hope that helps.

Example of one of my settings for one particular hot end M301 P19.93 I1.51 D65.71 That gets entered on the terminal and then M500 to save it.