So say you have a closed hi-hat choking an open high-hat, because they’re both assigned to Excl group 1 with polyphony = 1.
You don’t need to set the polyphony to 1 for this to work.
Usually the factory drum kits use oneshot mode for samples, key polyphony 4 and exlusive groups as needed…
If you set the voice group polyphony to 1 and play the same drum sample in quick succesion, each sample playback will cut off the previous one as soon as it starts. It may be cool if that’s what you want, but it can sound weird especially with a bit longer samples.
If you set the key polyphony to 4 (or any other reasonable number), you can leave the voice group polyphony at its default 128 and only use the exclusive groups for choking.