I use 100 if conditions permit, but frequently use auto ISO as I shoot handheld in dim environments. Depending on subject, up to 16000 is usable. I’ve been using the meter setting “preserve highlights” which tends to shift the exposure towards lower ISO to keep highlights within range. It works pretty well, but sometimes will need pulling up the shadows a bit. In contrast to Rosco I care more about depth of field and ability to minimize camera shake/subject movement than I do about sensitivity.
Try it out and decide for yourself. The Z6 has lots of latitude to play with.