<p>Since I have lots of PETG, I ran tuning to 230 °C (average temp for my filaments).
What is it good for, in terms of temperature ranges?</p>
<p>For the same printer configuration, and just different filaments, will I need to run it again and again?
Let's assume that I'll be printing between 200 °C and 240 °C.</p>
<p><a href="https://i.stack.imgur.com/SOVjm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SOVjm.png" alt="marlin pid via octoprint" /></a></p>

It's not a straight answer, but you don't have to run PID tuning every time you decide to print with different temperature. (Until you change something in a hardware near or related to the hotend.)
You can tune PID for different temperatures and grab necessary values, for example:
```
```
M303 C16 D1 E0 S190
22:14:31.872 > PID Autotune finished! Put the last Kp, Ki and Kd constants from below into Configuration.h
22:14:31.886 > #define DEFAULT_Kp 30.87
22:14:31.886 > #define DEFAULT_Ki 3.06
22:14:31.886 > #define DEFAULT_Kd 77.75
```
```
and then store respective G-code commands (like
```
M301 P30.87 I3.06 D77.75
```
) as few different "PID profiles" as new entries in
custom menu for Marlin
or
menu.cfg for Klipper
for quick switching.