It depends how you’re using it.
There just isn’t a simple answer that will help.
There are people using it with settings as low as 3-10-16 and as high as 40-90-30.
A very good approach, with indicators, is to start from “This is what I want to display, for my system - which indicator can do that and how do I use it, and with which settings?”
A terribly bad approach is “Here’s an indicator that people use - what settings do I want and what will it show me?”
Having said that, for most people, especially those without a lot of experience, slower settings are usually better than faster.
It’s true that a shorter lookback period will show momentum reversals closer to the highs and lows of the price-swings, but it will also have far more false signals.
Momentum oscillators mostly don’t represent price trends, only momentum trends.
Price and momentum often don’t trend simultaneously.
If you don’t quite understand the last few sentences yet, you shouldn’t be using MACD at all. Honestly.