I am using the Surge synthesizer. Its delay effect seems really different than Primer.
This page documents it --- https://surge-synthesizer.github.io/manual/#delay
Primer has a single "spread" option from 0 to 1. I've seen this in other synths too, like the Jun-6 V that I've also played with. (Aside, I haven't been able to find any explanation of what this [0,1] value actually means at the level of the DSP math.)
But Surge has more options... a separate time for the left and right and a crossfeed mechanism. I've read some articles about these. By having different left & right times, then the echo will cycle more quickly in one. And by having a crossfeed (but no normal feedback), then you can create a "ping-pong effect" which seems to be similar to a spread, because the signal will go back and forth between the two sides.
Is there a straight-forward to translate the [0,1] "spread" knob into what a synth like Surge offers? [Feel free to link me if it is annoying to re-type an explanation from an article somewhere.]