Sometimes pedal UIs are obtuse because a single knob will control multiple parameters under the hood and there isn't a succinct way to describe it's effect that

Sometimes pedal UIs are obtuse because a single knob will control multiple parameters under the hood and there isn't a succinct way to describe it's effect that will fit on the pedal. In that case you'll need to read the manual. And then sometimes manufacturers give common parameters colorful names that illustrate the musical effect while not being 100% accurate. For example, a fuzz pedal I own has a "pinch" knob which functions like a gate, even though it's not technically a gate. Again, read the manual if it's not obvious. As for your example of a flanger or phaser, those tend to have a handful of common parameters that you'll encounter across all variations (delay time, feedback, depth, rate, and dry/wet). For anyone who has experience with these devices they will already know that (by convention) depth controls LFO amplitude and rate controls LFO frequency. If you don't know this then it's very likely that you're new to the world of audio effects and simply need to (once again) read the manual. There's only so much information that you can put on the face of a guitar pedal.