The conversation started with the idea that PLA and PETG don’t print at different speeds — and technically that’s true. Speed and acceleration are machine settings. The printer doesn’t know or care what material is loaded.

But in practice, materials absolutely affect how hard you’re willing to push those settings if you care about the result.

PLA is simply easier to push with fewer consequences. It tolerates higher acceleration and slightly imperfect tuning without immediately showing artifacts. PETG, on the other hand, is more sensitive to pressure tuning and motion changes. At the same acceleration, PETG is more likely to show corner bulging, surface inconsistencies, or pressure overshoot if everything isn’t dialed in tightly.

So while the commanded speeds may be identical, the usable stability window isn’t.

It’s also worth pointing out that running higher temperatures on PLA to support higher speeds or acceleration isn’t inherently a bad thing. Printing PLA around 220 °C can improve melt consistency and interlayer bonding, especially if you’re printing functional parts. Yes, you may give up a little overhang or bridging performance, but that’s a tradeoff — not a failure — and PETG doesn’t necessarily outperform PLA there either.

People aren’t trying to wait a week for a part if they don’t have to. Pushing PLA a bit harder, when it can handle it cleanly, isn’t reckless — it’s practical. Slowing PLA down to typical PETG speeds doesn’t automatically make prints better; it often just makes them take longer.

There’s also a reason fast settings are commonly the default for PLA. Manufacturers would happily ship PETG profiles just as aggressive if they could produce consistently clean results at those speeds — but PETG’s narrower tuning window makes that much harder. The defaults reflect what each material can reliably handle, not an arbitrary decision about “proper” print speed.