If you can explain your reasoning and you haven't burned bridges there is no minimum amount of time. I know someone who left a role after 2 months without issue. However, if it's a pattern then I might start to raise my eyebrows a bit.
Hiring is all about telling your story, whatever that story is. If it includes short stints in a variety of roles then that's your narrative.
I think it also helps when I explain during interviews, was that I left one position so I could move to a different town.
Absolutely. There are a number of reasons for leaving a job, many of them completely non-controversial. That's why there is no hard and fast rule.
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